Smanjili smo ne samo troškove nego i manjak.

Because smo is a clitic, and Serbian clitics usually take the second position in the sentence or clause.

So:

• Smanjili smo = literally something like Reduced have-we
• natural English order would be We have reduced

In Serbian, the full subject pronoun mi is often omitted because the verb form already shows the person and number. So smo just goes into its normal clitic position after the first element:

• Smanjili smo troškove. = We reduced the costs.

You can also say:

• Mi smo smanjili troškove.

Here mi is included for emphasis or contrast.

Smanjili smo is the past tense (perfect) of the verb smanjiti.

It is made of:

• smanjili = past participle, masculine plural
• smo = we are/have auxiliary form used to build the past tense

Together:

• smanjili smo = we reduced / we have reduced

The participle is plural because the implied subject is we.

If the speakers were all female, you could also hear:

• Smanjile smo...

That is the feminine plural form.

Because smanjiti is the perfective verb, and it presents the reduction as a completed whole.

• smanjiti = to reduce, to make smaller/lower, completed action
• smanjivati = to be reducing, to reduce repeatedly or over time, ongoing/habitual action

So:

• Smanjili smo... suggests a completed result: we reduced...
• Smanjivali smo... would suggest something more like we were reducing or we used to reduce

In this sentence, the speaker is talking about an achieved result, so perfective smanjiti fits naturally.

Because troškove is the accusative plural, and it is the direct object of the verb smanjiti.

The noun is:

• singular: trošak = cost, expense
• plural nominative: troškovi = costs
• plural accusative: troškove

Since we reduced what? → costs, Serbian uses the accusative:

• Smanjili smo troškove.

So:

• troškovi = subject form
• troškove = object form

Because manjak is also a direct object here, but it is a masculine inanimate singular noun, and for many masculine inanimate nouns, the accusative singular is identical to the nominative singular.

So:

• nominative: manjak
• accusative: manjak

That is why the sentence says:

• nego i manjak

not because it is a subject, but because this noun happens to have the same form in nominative and accusative.

By contrast, compare a masculine animate noun:

• student (nominative)
• studenta (accusative)

But with inanimate nouns like manjak, the form usually stays the same in the accusative singular.

It means not only ... but also ...

This is a very common Serbian structure:

• ne samo X nego i Y
• not only X but also Y

In your sentence:

• ne samo troškove nego i manjak
• not only costs but also the deficit/shortage

It highlights that the second thing is an additional, maybe even surprising, achievement.

You may also see:

• ne samo ... već i ...

That means the same thing in many contexts.

They work together as part of the fixed pattern:

• ne samo ... nego i ...

Here:

• nego introduces the second element after the negative opening ne samo
• i means also/even

So the combination is not just random word-by-word addition. It is a set phrase meaning:

• not only ..., but also ...

If you remove i, the sentence can still sometimes be understandable, but nego i is the standard, natural pairing here.

Because Serbian often drops subject pronouns when they are already clear from the verb form.

In:

• smanjili smo

the ending and auxiliary already show we.

So mi is unnecessary unless you want emphasis, contrast, or clarity.

Compare:

• Smanjili smo troškove. = We reduced the costs.
• Mi smo smanjili troškove. = We reduced the costs (with extra emphasis on we)

This is very normal in Serbian.

Yes. Serbian word order is fairly flexible, though not completely free. This sentence could be rearranged for emphasis.

For example:

• Ne samo troškove nego i manjak smo smanjili.
• Troškove smo smanjili, ali i manjak.
  (a bit different in structure and tone)

Still, the original:

• Smanjili smo ne samo troškove nego i manjak.

is natural and clear.

The original word order puts the focus on the action first, then introduces the not only ... but also ... contrast.

Manjak can mean shortage, lack, deficit, or shortfall, depending on context.

Common meanings include:

• a shortage of something
• a financial deficit
• a missing amount

So in this sentence, manjak could mean:

• deficit
• shortfall
• shortage

If the context is finances or budgeting, deficit or shortfall is often the best translation.

Both can work.

• trošak = cost / expense
• troškovi = costs / expenses

The best English choice depends on context:

• business/accounting context: expenses
• general budgeting context: costs
• production/economic context: costs

So the sentence could mean:

• We reduced not only costs but also the deficit.
• We reduced not only expenses but also the shortfall.

Both are possible, depending on what the broader context is.

In a structure like ne samo ... nego i ..., Serbian often writes it without a comma when it is connecting sentence parts rather than full clauses.

So:

• Smanjili smo ne samo troškove nego i manjak.

is perfectly normal.

If the structure becomes longer or more clause-like, punctuation can feel more variable in practice, but in a simple sentence like this, no comma is standard and natural.

Yes, it can suggest that.

The structure ne samo X nego i Y often presents Y as an important addition, sometimes even the more noteworthy one.

So:

• not only costs, but also the deficit

can sound like:

• reducing costs was already good,
• but reducing the deficit too is an extra achievement.

That effect comes from the structure itself, not from any special verb form.