Pour peu que le nom soit peu clair, renommons le fichier.

Pour peu que is a fixed expression that introduces a condition. In many contexts, it means something like if, provided that, or if only ... even a little.

In this sentence, it gives the idea that a small degree of unclearness is enough: if the name is even a bit unclear, that is sufficient reason to rename the file.

It is more formal and literary than plain si.

Because pour peu que is followed by the subjunctive.

So with être, you get:

• il est = indicative
• qu'il soit = subjunctive

Here, le nom soit peu clair is the subjunctive clause required by pour peu que.

Soit is the present subjunctive form of être for il / elle / on.

So:

• que je sois
• que tu sois
• qu'il / elle soit
• que nous soyons
• que vous soyez
• qu'ils / elles soient

In this sentence, le nom is singular, so French uses soit.

They do not play the same role.

The first peu is part of the fixed expression pour peu que. You should learn that as a whole.

The second peu is the ordinary adverb meaning not very or not enough in peu clair.

So this is not really a case of the same word being repeated with the same function. One belongs to the conjunction, and the other modifies clair.

Peu clair means not very clear, insufficiently clear, or simply unclear.

It often suggests that something lacks clarity, rather than being only slightly clear in a positive sense.

That is why peu clair works naturally here, while un peu clair would sound odd in most contexts.
Compare:

• peu clair = not clear enough / unclear
• très clair = very clear
• pas clair = not clear

Yes. Renommons is the 1st person plural imperative of renommer.

It means let's rename.

French has an imperative for nous, used when the speaker includes themself in the action:

• Renommons le fichier = let's rename the file

Notice that the subject pronoun is omitted in the imperative.
So:

• Nous renommons le fichier = we are renaming / we rename the file
• Renommons le fichier = let's rename the file

Here, le nom refers to the file's name, while le fichier refers to the file itself.

So the logic is:

• if the name is unclear,
• let's rename the file

In context, French often shortens le nom du fichier to simply le nom when it is obvious what name is being discussed.

Yes, that would be grammatical and more straightforward.

• Si le nom est peu clair, renommons le fichier.

That version is more neutral and direct.
The original with pour peu que sounds more formal and can suggest that even a slight lack of clarity is enough to justify renaming.

So the difference is mostly one of style and nuance, not basic meaning.

It is correct, but it sounds somewhat formal, written, or instructional.

In everyday speech, many speakers might choose something simpler, such as:

• Si le nom n'est pas clair, renommons le fichier.
• Si le nom est ambigu, renommons le fichier.
• Si le nom n'est pas très clair, on renomme le fichier.

So the original is natural enough, but it is not especially casual.

The comma separates the initial conditional clause from the main clause:

• Pour peu que le nom soit peu clair, = subordinate clause
• renommons le fichier = main clause

When a longer condition or introductory clause comes first, French often uses a comma to make the sentence easier to read. It is very natural here.