Money? Think nothing of it! (3)

I believe the answer is:

oof

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

'nothing of it' is the wordplay.
'nothing' becomes 'O' (O resembles 0).
'of' becomes 'o''.
'it' becomes 'f' (I am not sure about this - if you are sure you should believe this answer much more).
'o'+'o'+'f'='OOF'

Can you help me to learn more?

I've seen this clue in the Evening Standard.

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