Sound rebound (4)
I believe the answer is:
echo
'sound rebound' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for echo that I've seen before include "Rebounding sound" , "Evocation" , "Reflected radar beam" , "one catches on the rebound?" , "'Greek nymph, she pined away until only her voice remained (4)'" .)