As a group; all together (2,5)
I believe the answer is:
en masse
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">as a group</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >'<span class="explanation-format__original">all together</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for en masse that I've seen before include "In a group U altogether" , "All together (Fr.)" , "Sees man (anag.)" , "All together - in France (2.5)" , "All together as a group" .)