Fine tune the first seven days of audio (5)

I believe the answer is:

tweak

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'fine tune' is the definition.
(I've seen this before)

I don't understand how the rest of the clue works.

(Other definitions for tweak that I've seen before include "Nip" , "Make fine adjustment" , "Change slightly" , "Twitch" , "Minor change" .)

I've seen this clue in the Sydney Morning Herald.

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