Depraved emperor (4)
I believe the answer is:
nero
'depraved emperor' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for nero that I've seen before include "Roman Emperor notorious for vice and luxury" , "Imperial Roman fiddler" , "Ancient Roman emperor" , "Roman emperor on the fiddle?" , "Roman arsonist and fiddler" .)