Redcoat supporter (4)
I believe the answer is:
tory
'redcoat supporter' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tory that I've seen before include "Traditionalist" , "English Conservative politician or Donegal island" , "Politician; tyro (anag.)" , "blue" , "Opponent of 8 Down and 14 Across, partner of 14 Down?" .)