It's not good (4)
'it's not good' is the definition.
(evil is the opposite of good)
This is the entire clue.
(Other definitions for evil that I've seen before include "Extremely unpleasant" , "Great wickedness" , "source of harm" , "Villainy" , "Wicked - social problem" .)
'it's not good' is the definition.
('ill' is the opposite to 'good')
This is all the clue.
(Other definitions for ill that I've seen before include "Harmful" , "Harm" , "Wicked" , "In a bad way" , "state, briefly" .)