Performer runs through short musical piece (4)
I believe the answer is:
turn
'performer' is the definition.
('turn' can mean a performer as well as their act)
'runs through short musical piece' is the wordplay.
'runs' becomes 'r' (cricket abbreviation).
'through' means one lot of letters goes inside another (I've seen this in other clues).
'short' means to remove the last letter.
'musical piece' becomes 'tune'.
'tune' with its final letter removed is 'tun'.
'r' put into 'tun' is 'TURN'.
(Other definitions for turn that I've seen before include "rotation" , "Revolve - go off" , "Revolve; act" , "Sour" , "Move around an axis, or change" .)