Button to help motor racing lady (4)

I believe the answer is:

fifi

I'm a little stuck... Click here to teach me more about this clue!

'lady' is the definition.

'button to help motor racing' is the wordplay.
I cannot really see how this works, but
'motor racing' could be 'fi' (FI resembles F1, Formula 1) and 'fi' is found within the answer.
This may be the basis of the clue (or it may be nonsense).

Can you help me to learn more?

I've seen this clue in The Telegraph.

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