Laugh-fest (4)
I believe the answer is:
riot
'laugh-fest' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for riot that I've seen before include "Wild disturbance by crowd of people" , "Uprising" , "scream" , "Disturbance by unruly mob" , "Public act of violence by an unruly mob" .)