Wealth? Think nothing of it! (3)

I believe the answer is:

oof

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'wealth? think' is the definition.
The definition suggests a singular noun which matches the answer.

'nothing of it' is the wordplay.
'nothing' becomes 'O' (looks like zero - 0).
'of' becomes 'o''.
'it' becomes 'f' (I can't explain this - if you can you should give a lot more credence to this answer).
'o'+'o'+'f'='OOF'

Can you help me to learn more?

I've seen this clue in the Evening Standard.

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