Sound of amusement (8)
I believe the answer is:
laughter
'sound of amusement' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for laughter that I've seen before include "Manifestation of mirth" , "Howling" , "It's said to be the best medicine" , "Hilarity" , "Sound of merriment" .)