Old artist after black, where red and white available? (7)
I believe the answer is:
bodegas
'where red and white available?' is the definition.
(bodegas sell wine)
'old artist after black' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'artist' becomes 'degas' (painter Edgar Degas).
'after' is a charade indicator (letters next to each other).
'black' becomes 'b' (abbreviation as in pencil classifications).
'o'+'degas'='odegas'
'odegas' after 'b' is 'BODEGAS'.
(Other definitions for bodegas that I've seen before include "Wine sellers" , "wine shops" , "shops abroad" , "wine-shops" , "Spanish shops" .)