Royal robe trim (6)
I believe the answer is:
ermine
'royal robe trim' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ermine that I've seen before include "Fur for an English judge" , "Fur trimming on royal robes" , "'Trimming on royal robes, say (6)'" , "special trimmings" , "Fur-bearing mammal" .)