Coins demanding general acceptance (4,8)

I believe the answer is:

hard currency

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'coins' is the definition.
Although both the answer and definition are nouns, they are not in the same form of the noun.

'demanding general acceptance' is the wordplay.
'demanding' becomes 'hard' (similar in meaning).
'general acceptance' becomes 'currency' (I've seen this before).
'hard'+'currency'='HARD CURRENCY'

Can you help me to learn more?

(Other definitions for hard currency that I've seen before include "Money in demand from foreigners" , "Very stable means of exchange" .)

I've seen this clue in The Telegraph.

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