Sound of derision (5)
I believe the answer is:
snort
'sound of derision' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for snort that I've seen before include "Take illegal drug" , "Take cocaine (sl.)" , "drink, a quickie" , "Noisily express indignation" , "Chortle" .)