Wicked, sinful (3)
I believe the answer is:
bad
This clue is a double definition.
'wicked' is the first definition.
(similar in meaning)
'sinful' is the second definition.
(I've seen this in another clue)
(Other definitions for bad that I've seen before include "Evil, below standard or off" , "Stinking" , "Severe; of low standard" , "Rotten, evil" , "Substandard" .)