Lion’s ruff (4)
I believe the answer is:
mane
'lion's ruff' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for mane that I've seen before include "Animal neck-hair" , "Animal's neck hair" , "Long shaggy hair" , "Long thick hair" , "Lion or horse's 10 Across" .)