Stoat fur (6)
I believe the answer is:
ermine
'stoat fur' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for ermine that I've seen before include "White fur worn by some judges" , "Animal with brown fur that turns white in winter" , "'Trimming on royal robes, say (6)'" , "Regal fur" , "White fur of stoat" .)