Credit and debit cards (7)
I believe the answer is:
plastic
'credit and debit cards' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for plastic that I've seen before include "Credit and debit cards" , "Like some cards" , "Ubiquitous synthetic material" , "Credit cards etc" , "Euphemism for a credit card" .)