Revealed by soldiers after party in the open air (7)
I believe the answer is:
outdoor
'in the open air' is the definition.
(I've seen this before)
'revealed by soldiers after party' is the wordplay.
'revealed' becomes 'out' (I've seen this in other clues**).
'by' means one lot of letters go next to another.
'soldiers' becomes 'or' (Other Rank).
'after' says to put letters next to each other.
'party' becomes 'do' (do is a kind of party).
'or' put after 'do' is 'door'.
'out'+'door' is 'OUTDOOR'.
(Other definitions for outdoor that I've seen before include "exposed to the elements" , "This sport is not under a roof" , "Used in the open air" , "in the garden, say" , "External" .)