Small vehicle, a black Beetle? (6)
I believe the answer is:
scarab
'beetle?' is the definition.
(I know that scarab is a type of dung beetle)
'small vehicle a black' is the wordplay.
'small' becomes 's' (abbreviation - e.g. clothes size).
'vehicle' becomes 'car' (car is a kind of vehicle).
'black' becomes 'b' (as in pencil classifications).
's'+'car'+'a'+'b'='SCARAB'
(Other definitions for scarab that I've seen before include "divine thing once" , "divine creature" , "Large dark beetle" , "Old abuse" , "Beetle revered in ancient Egypt" .)