Credit card company with stock to purchase, including wine (7)
I believe the answer is:
plastic
'credit card' is the definition.
(I know that credit card can be written as plastic)
'company with stock to purchase including wine' is the wordplay.
'company with stock to purchase' becomes 'plc' (public limited company).
'including' is an insertion indicator.
'wine' becomes 'asti' (Italian wine).
'plc' placed around 'asti' is 'PLASTIC'.
(Other definitions for plastic that I've seen before include "Credit and debit cards" , "Euphemism for a credit card" , "Generic name for certain synthetic materials" , "Synthetic polymer" , "Synthetic substance" .)