Sleep sound (5)
I believe the answer is:
snore
'sleep sound' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for snore that I've seen before include "How to keep someone awake while sleeping?" , "Noise made while asleep" , "Grunting sound" , "Raucous sound while sleeping" , "Make noises sleeping" .)