Fine-tunes (6)
I believe the answer is:
tweaks
'fine-tunes' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for tweaks that I've seen before include "Pinches and twists sharply" , "Pinches and twists, perhaps nose" , "Pinches and twists, maybe a nose" , "Improves a little" , "Makes little adjustments" .)