Mistreats (6)
I believe the answer is:
'mistreats' is the definition.
('abuse' can be a synonym of 'mistreat')
This is all the clue.
(Other definitions for abuses that I've seen before include "Reviles or takes undue advantage." , "Treats cruelly" , "Maltreats people or things" , "Reviles and insults" , "Curses" .)