Charm, finish and musical ability (6)
I believe the answer is:
endear
'charm' is the definition.
(I've seen this before)
'finish and musical ability' is the wordplay.
'finish' becomes 'end' ('end' can be a synonym of 'finish').
'and' is a charade indicator (letters next to each other).
'musical ability' becomes 'ear' (I've seen this before).
'end'+'ear'='ENDEAR'
(Other definitions for endear that I've seen before include "Neared in order to charm" , "Make loveable" , "Give popularity to" , "Neared (anag.)" , "Cause to like" .)