Working only for money (4,8)

I believe the answer is:

coin operated

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'working' is the definition.
Both the answer and definition are adjectives.
Maybe there's a link between them I don't understand?

'only for money' is the wordplay.
'only' becomes 'operated' (I can't explain this - if you can you should give a lot more credence to this answer).
'for' is a charade indicator (letters next to each other) (I've seen this in other clues).
'money' becomes 'coin' (coin is a type of money).
'operated' put after 'coin' is 'COIN-OPERATED'.

Can you help me to learn more?

I've seen this clue in the Evening Standard.

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