Man’s overcoat (6)
I believe the answer is:
ulster
'man's overcoat' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for ulster that I've seen before include "Overcoat; Northern Ireland" , "old province" , "A heavy coat" , "Overcoat; Irish region" , "Cloak for an Irish province" .)