Sound of merriment (8)
I believe the answer is:
laughter
'sound of merriment' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for laughter that I've seen before include "Manifestation of mirth" , "Hilarity" , "Infectious thing" , "Manifestation of amusement" , "Sound of merriment" .)