Run amok (4)
I believe the answer is:
riot
'run amok' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for riot that I've seen before include "Violent crowd disturbance" , "Disturbance of the peace by many" , "Rampage" , "Disturbance by unruly mob" , "Violent disturbance by mob" .)