Repeat the choral part (4)
I believe the answer is:
echo
'repeat' is the definition.
(I know that repeat can be written as echo)
'the choral part' is the wordplay.
'part' indicates the answer is hidden within the clue.
'ECHO' is hidden within 'the choral'.
(Other definitions for echo that I've seen before include "Return of sound waves" , "Rebounding sound" , "letter we hear" , "Radio operator's word for 'E'" , "Marked by heat" .)