Friend of the piano man? (3)
I believe the answer is:
pal
'friend' is the definition.
(pal can mean a friend)
'piano man?' is the wordplay.
'piano' becomes 'p' (musical abbreviation).
'man?' becomes 'al' (man's name).
'p'+'al'='PAL'
'of the' is the link.
(Other definitions for pal that I've seen before include "Bud" , "Brother" , "Crony" , "Friend (colloq.)" , "Mate, informal friend" .)