White-coated stoat (6)
I believe the answer is:
ermine
'white-coated stoat' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for ermine that I've seen before include "Ceremonial fur" , "White fur from kind of 25 Across - judges may wear it" , "Animal with brown fur that turns white in winter" , "Fur-bearing mammal" , "Fur for an English judge" .)