Abuse the latter unfairly, to a degree (8)
I believe the answer is:
maltreat
'abuse' is the definition.
('maltreat' can be a synonym of 'abuse')
'the latter unfairly to a degree' is the wordplay.
'unfairly' indicates anagramming the letters (I've seen this in other clues).
'to a' means one lot of letters go next to another (I've seen this in other clues).
'degree' becomes 'ma' (Master of Arts is a type of degree).
'latter' with letters rearranged gives 'ltreat'.
'ltreat' put after 'ma' is 'MALTREAT'.
(Other definitions for maltreat that I've seen before include "Act badly or cruelly towards someone" , "Use unkindly" , "Use roughly" , "Behave badly or cruelly towards" , "Harm" .)