Repeat in the choir (4)
I believe the answer is:
echo
'repeat' is the definition.
(I know that repeat can be written as echo)
'in the choir' is the wordplay.
'in' indicates the answer is hidden within the clue.
'ECHO' can be found hidden inside 'the choir'.
(Other definitions for echo that I've seen before include "Say again or imitate" , "Sound heard before" , "one catches on the rebound?" , "next to delta" , "In Roman mythology, the nymph who loved Narcissus" .)