Vehicle black and dirty not an eyesore (9)
I believe the answer is:
carbuncle
'eyesore' is the definition.
(I have seen 'Architectural eyesore ' mean 'carbuncle' so perhaps 'eyesore' could also mean 'carbuncle')
'vehicle black and dirty not an' is the wordplay.
'vehicle' becomes 'car' (car is a kind of vehicle).
'black' becomes 'b' (as in pencil classifications).
'and' is a charade indicator (letters next to each other).
'dirty' becomes 'unclean' (synonyms).
'not' suggests deleting specific letters.
'unclean' with 'an' removed is 'uncle'.
'car'+'b'+'uncle'='CARBUNCLE'
(Other definitions for carbuncle that I've seen before include "National Gallery's Sainsbury Wing?" , "growth" , "Bright red gem; boil" , "Sort of boil; a gem" , "Architectural eyesore" .)