Resounding section of the chorus (4)
I believe the answer is:
echo
'resounding' is the definition.
(thesaurus)
'section of the chorus' is the wordplay.
'section of' indicates a hidden word.
'ECHO' is hidden within 'the chorus'.
(Other definitions for echo that I've seen before include "Resound; (radar) return" , "Reflected radar beam" , "'Greek nymph, she pined away until only her voice remained (4)'" , "Imitate -- a nymph" , "Reflection of sound waves" .)