Piano skills for piece (4)
I believe the answer is:
part
'piece' is the definition.
(synonyms)
'piano skills' is the wordplay.
'piano' becomes 'p' (musical abbreviation).
'skills' becomes 'art'.
'p'+'art'='PART'
'for' is the link.
(Other definitions for part that I've seen before include "Fraction of the whole - separate" , "Portion of a whole" , "Some; break" , "Member" , "Component; divide" .)