Drive off revolting social outcast (5)
I believe the answer is:
repel
'drive off' is the definition.
(synonyms)
'revolting social outcast' is the wordplay.
'revolting' says the letters should be written in reverse.
'social outcast' becomes 'leper' (someone with leprosy).
'leper' back-to-front is 'REPEL'.
(Other definitions for repel that I've seen before include "Drive or force back" , "push off" , "Sicken" , "Successfully resist" , "Hold off" .)