Innkeeper in the army? (4)
I believe the answer is:
host
I believe this clue is a double definition.
'innkeeper' is the first definition.
(I've seen this before)
'army?' is the second definition.
(host is a kind of army)
'in the' is the link.
(Other definitions for host that I've seen before include "great many!" , "Landlord; army" , "lot of people" , "Entertain" , "Army - innkeeper" .)