Maltreats (6)
I believe the answer is:
abuses
'maltreats' is the definition.
('abuse' can be a synonym of 'maltreat')
This is all the clue.
(Other definitions for abuses that I've seen before include "Reviles and insults" , "Reviles or takes undue advantage." , "Curses" , "Employs or deals with incorrectly" , "Treats cruelly" .)