Note match fix! (6)
I believe the answer is:
repair
'fix' is the definition.
('repair' can be a synonym of 'fix')
'note match' is the wordplay.
'note' becomes 're'.
'match' becomes 'pair' ('pair' can be a synonym of 'match').
're'+'pair'='REPAIR'
(Other definitions for repair that I've seen before include "Mend - go" , "darn?" , "Restore to working condition" , "Fix, mend" , "Maintain" .)