Repeat section of the chorus (4)
I believe the answer is:
echo
'repeat' is the definition.
('echo' can be a synonym of 'repeat')
'section of the chorus' is the wordplay.
'section of' says the answer is hidden in the clue.
'ECHO' can be found hidden inside 'the chorus'.
(Other definitions for echo that I've seen before include "Nymph; E (radio comms.)" , "repercussion" , "Say again or imitate" , "Return of sound waves" , "Greek nymph, spurned by Narcissus, who pined away until only her voice remained" .)