White fur of the stoat (6)
![Ross](/clue/static/ross-mug.min.png)
I believe the answer is:
ermine
(Other definitions for ermine that I've seen before include "'Trimming on royal robes, say (6)'" , "special trimmings" , "White-coated stoat" , "White fur from kind of 25 Across - judges may wear it" , "White fur worn by some judges" .)