As a group; all together (2,5)
I believe the answer is:
en masse
This clue is a double definition.
'as a group' is the first definition.
(synonyms)
'all together' is the second definition.
(I've seen this before)
(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" .)