Repeat in the choir (4)
I believe the answer is:
echo
'repeat' is the definition.
(synonyms)
'in the choir' is the wordplay.
'in' says the answer is hidden in the clue.
'ECHO' is hidden in the letters of '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" .)