Lion's crowning glory (4)
I believe the answer is:
mane
'lion's crowning glory' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for mane that I've seen before include "Name for hair on horse's neck" , "Long flowing hair" , "Animal's neck hair" , "(Lion's) hair on neck" , "Lion or horse's 10 Across" .)