Lachrymator (4,3)
I believe the answer is:
tear gas
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">lachrymator</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for tear gas that I've seen before include "Crowd disperser" , "Used by police against rioters, irritates eyes" , "Riot control agent" , "Lacrimator" , "Riot controller" .)