Military guard (6)
I believe the answer is:
sentry
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">military guard</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 sentry that I've seen before include "Sentinel, look-out" , "Look-out, guard" , "One keeps guard" , "Soldier on guard" , "Military lookout" .)