Flee in small vehicle with rejected agent (7)
I believe the answer is:
scarper
'flee' is the definition.
(I know this)
'small vehicle with rejected agent' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'vehicle' becomes 'car' (car is a kind of vehicle).
'with' says to put letters next to each other.
'rejected' shows that the letters should be reversed in order.
'agent' becomes 'rep' (short for representative).
'rep' backwards is 'per'.
's'+'car'+'per'='SCARPER'
'in' is the link.
(Other definitions for scarper that I've seen before include "Run away (sl.)" , "Vamoose" , "Take to one's heels, cut and run" , "Damage" , "bolt" .)