Synthetic; credit card (7)
I believe the answer is:
plastic
I believe this clue is a double definition.
'synthetic' is the first definition.
(I've seen this in another clue)
'credit card' is the second definition.
(I know that credit card can be written as plastic)
(Other definitions for plastic that I've seen before include "Ubiquitous synthetic material" , "Synthetic polymer" , "Compliant" , "Euphemism for a credit card" , "Like some cards" .)