One of the Four Horsemen of the Apocalypse (3)
I believe the answer is:
war
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">one of the four horsemen of the apocalypse</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 war that I've seen before include "State of armed conflict" , "Battle" , "Hostile situation" , "State of armed struggle" , "Large-scale conflict" .)