Crowd disperser (7)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">crowd disperser</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for tear gas that I've seen before include "Riot control means" , "Riot control weapon" , "Riot control agent" , "'It can be used to disperse crowds (4,3)'" , "Airlike substance that irritates the eyes, used in riots" .)