A fix? Correct (5)
I believe the answer is:
amend
'correct' is the definition.
(amending is a kind of correcting)
'a fix?' is the wordplay.
'fix?' becomes 'mend' (synonyms).
'a'+'mend'='AMEND'
(Other definitions for amend that I've seen before include "Correct or alter to improve" , "Make minor improvements to (a document)" , "Make minor changes to" , "Change for the better" , "Change to improve" .)