It's revolting, drive away fast! (9)
I believe the answer is:
repellent
'it's revolting' is the definition.
('repellent' can be a synonym of 'revolting')
'drive away fast' is the wordplay.
'drive away' becomes 'repel' (I've seen this before**).
'fast' becomes 'lent' (I've seen this before).
'repel'+'lent'='REPELLENT'
(Other definitions for repellent that I've seen before include "Causing distaste" , "Repugnant, loathsome" , "Odious" , "It arouses distaste or drives insects away" , "Disgusting, or substance that drives away insects" .)