Mob scene (4)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">mob scene</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for riot that I've seen before include "Public act of violence by an unruly mob" , "Wild revelry" , "unrestrained revelry" , "Lavish display (of colour)" , "Violent crowd disturbance" .)