Plead to play the piano part (5)
I believe the answer is:
pedal
'the piano part' is the definition.
'pedal' can be an answer for 'part' (I have seen 'part of organ' mean 'pedal' so perhaps 'part' could also mean 'pedal'). I'm unsure of the 'the piano' bit.
'plead to play' is the wordplay.
'to play' indicates anagramming the letters.
'plead' with letters rearranged gives 'PEDAL'.
Can you help me to learn more?
(Other definitions for pedal that I've seen before include "Foot-operated lever" , "Foot control" , "Plead for bike pusher" , "related to feet" , "One of two a cyclist needs" .)