Hun retter sin kladde igen, fordi hun vil være sikker på, at alt er klart.

Because sin refers back to the subject of the same clause.

In Hun retter sin kladde igen, the subject is hun, so Danish uses the reflexive possessive sin to mean her own.

• sin kladde = her own draft
• hendes kladde would usually mean someone else’s draft, not the subject’s own

This is a very common Danish pattern:

• Hun vasker sin bil = She washes her own car.
• Hun vasker hendes bil = She washes her car, meaning another woman’s car.

Since the draft belongs to the same person as hun, sin is correct.

Kladde means a draft, rough copy, or working version of a text.

In this sentence, it suggests something she has written and is now revising or correcting.

Common related words:

• en kladde = a draft
• et udkast = a draft, often a bit more formal
• en renskrift = a clean/final copy

So sin kladde means her draft or her rough draft.

Retter is the present tense of at rette.

Here it means something like:

• corrects
• edits
• revises
• fixes

So Hun retter sin kladde igen means she is going through her draft and making corrections or improvements.

Danish at rette can be used in several ways depending on context:

• rette fejl = correct mistakes
• rette en tekst = correct/edit a text
• rette noget til = adjust something

In this sentence, edit/revise is probably the most natural sense.

Igen means again, and in Danish it often comes after the object.

So this word order is very natural:

• Hun retter sin kladde igen.

Literally: She corrects her draft again.

You will often see adverbs like igen in this position:

• Jeg læser bogen igen.
• Han prøver det igen.

It is possible in some contexts to move adverbs around for emphasis, but the version in the sentence is the normal, neutral order.

Here vil means wants to, not future will.

So:

• hun vil være sikker på = she wants to be sure

In Danish, ville/vil often expresses desire or intention, not just future time.

Compare:

• Jeg vil spise = I want to eat
• Det vil regne i morgen = It will rain tomorrow

In your sentence, the meaning is clearly about intention: she is revising the draft because she wants to make sure everything is clear.

Because the expression is built that way in Danish.

• at være sikker på noget = to be sure of something
• at være sikker på, at ... = to be sure that ...

So:

• Jeg er sikker på det. = I am sure of it.
• Jeg er sikker på, at han kommer. = I am sure that he is coming.

In your sentence:

• hun vil være sikker på, at alt er klart
• literally: she wants to be sure of that everything is clear
• natural English: she wants to be sure that everything is clear

Even though English usually just says sure that, Danish normally keeps på.

This follows normal Danish comma usage.

The sentence has a main clause plus two subordinate clauses:

1. Hun retter sin kladde igen
2. fordi hun vil være sikker på
3. at alt er klart

Danish normally writes a comma before subordinate clauses, so you get:

• comma before fordi
• comma before at

This is very standard in written Danish.

Because after fordi you have a subordinate clause, and subordinate clauses in Danish do not use main-clause inversion.

Main clause pattern:

• Hun retter sin kladde igen.

Subordinate clause:

• fordi hun vil være sikker på ...

The subject hun comes before the finite verb vil.

This is normal Danish subordinate-clause structure.

A very useful comparison:

• Main clause: Nu retter hun sin kladde.
• Subordinate clause: ..., fordi hun nu retter sin kladde.

In the subordinate clause, the subject stays before the verb.

Because alt is grammatically neuter singular, and adjectives used predicatively agree with it.

The adjective is klar. Its neuter singular form is klart.

So:

• en tekst er klar
• et brev er klart
• alt er klart

Since alt behaves like a neuter singular word, Danish uses klart.

This is the same pattern as:

• Det er godt.
• Alt er fint.
• Det er muligt.

Here klart means clear in the sense of easy to understand.

So at alt er klart means:

• that everything is clear
• that everything is understandable
• that nothing is confusing

It does not mean clear as in weather.

In writing contexts, klart often means that the wording, structure, or message is easy for the reader to follow.

In careful standard Danish, at is normally kept here.

So the standard version is:

• ... sikker på, at alt er klart.

In informal spoken Danish, people may sometimes reduce or blur small words, but for learners, it is best to treat at as required in this structure.

Yes. Danish present tense often covers both the simple present and what English expresses with is/are + -ing, depending on context.

So:

• Hun retter sin kladde igen can mean
• She corrects her draft again or
• She is correcting/revising her draft again

Danish does have ways to emphasize ongoing action, but the simple present is very commonly used where English would choose a progressive form.

The sentence breaks down like this:

• Hun = subject
• retter = finite verb
• sin kladde = object
• igen = adverb
• fordi hun vil være sikker på = reason clause
• at alt er klart = clause depending on sikker på

So the overall pattern is:

main clause + reason clause + content clause

You can think of it as:

• She is revising her draft again
• because she wants to be sure
• that everything is clear

That layered structure is very common in Danish.