Roman army unit (6)
I believe the answer is:
legion
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">roman army unit</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for legion that I've seen before include "Roman military body of men" , "A great number in the Roman military unit" , "Host" , "France has a foreign one" , "Roman army grouping" .)