Canyon sound effect (4)
I believe the answer is:
echo
'canyon sound effect' 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 "Reminder" , "In Roman mythology, the nymph who loved Narcissus" , "letter we hear" , "Audio effect" , "Reverberate - nymph spurned by Narcissus" .)