Hostile force (5)
I believe the answer is:
enemy
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">hostile force</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for enemy that I've seen before include "Yemen (anag.)" , "Rival" , "other side (like 16)" , "Hostile opponent" , "Armed adversary" .)