Disturbance of the peace (4)
I believe the answer is:
riot
'disturbance of the peace' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for riot that I've seen before include "A wild public affray" , "Disturbance of the peace by many" , "Affray, fighting in the streets" , "The unruly may run this" , "very funny" .)