Coins but not notes? (4,8)
I believe the answer is:
hard currency
'coins but not' is the definition.
I can't judge whether this defines the answer.
'notes?' is the wordplay.
I cannot quite see how this works, but
'notes?' could be 'dc' and 'dc' is present in the answer.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for hard currency that I've seen before include "Very stable means of exchange" , "Money in demand from foreigners" .)