Wicked person, vile, rode off (8)
I believe the answer is:
evildoer
'wicked person' is the definition.
(I've seen this before)
'vile rode off' is the wordplay.
'vile' becomes 'evil' (I've seen this in another clue).
'off' is an anagram indicator.
'rode' with letters rearranged gives 'doer'.
'evil'+'doer'='EVILDOER'
(Other definitions for evildoer that I've seen before include "Malefactor" , "sinner" , "Over idle (anag) - villain" , "Rode live over morally bad person" , "miscreant" .)