Morally bad (4)
'morally bad' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for evil that I've seen before include "Depraved" , "Harmful; unlucky" , "Vile (anag) -- really bad" , "Wicked - sin" , "Morally corrupt" .)
(Other definitions for wicked that I've seen before include "very likely to cause harm" , "[SMASHING, COOL, DANDY]" , "Absorbed in enchanting" , "Morally bad or wrong" , "A candle is" .)
(Other definitions for corrupt that I've seen before include "Bent" , "doctor" , "Lacking in integrity" , "Wicked; rotten" , "base" .)