Wickedness really grips! (4)
I believe the answer is:
vice
'wickedness' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for vice that I've seen before include "Bad habit - it grips" , "Gripper - sin" , "Gripper - in place of - immorality" , "may have a powerful grip" , "Preposition meaning in place of" .)