People generally forget cup size on international swimwear (7)

I believe the answer is:

mankini

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

'generally forget cup size on international swimwear' is the definition.
I know nothing about this answer so I can't judge whether this works.

'people' is the wordplay.
I cannot really understand how this works, but
'people' could be 'man' (I've seen this in other clues) and 'man' is present in the answer.
This explanation may well be incorrect...

Can you help me to learn more?

I've seen this clue in The Independent.

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