Uniform colour (5)
I believe the answer is:
khaki
This clue is a double definition.
'uniform' is the first definition.
(I've seen this before)
'colour?' is the second definition.
(I've seen this before)
(Other definitions for khaki that I've seen before include "Military camouflage colour" , "Dull brown colour" , "Dullish brown colour" , "Military fabric" , "military-type clothing" .)