Ancient tribesman in a brownish uniform (3)
I believe the answer is:
hun
'ancient tribesman' is the definition.
The definition and answer can be both people as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'in a brownish uniform' is the wordplay.
'in' indicates the answer is hidden within the clue.
'HUN' can be found hidden inside 'brownish uniform'.
Can you help me to learn more?
(Other definitions for hun that I've seen before include "One of fourth to fifth century invaders of Europe" , "Ancient invader" , "Eg, Attila" , "Barbarian" , "One led by Attila" .)