Massacre, slaughter (6)
I believe the answer is:
pogrom
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">massacre</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >'<span class="explanation-format__original">slaughter</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I have seen 'Mass slaughter ' mean 'pogrom' so perhaps 'slaughter' could also mean 'pogrom')</span><br/ ><br/ ></span>
(Other definitions for pogrom that I've seen before include "Mass slaughter" , "Organised massacre of Jews" , "Organised persecution of an ethnic group" , "Racial massacre" , "An organised massacre of a people" .)