Lots of people have made quite a few singles (4,1,3)

I believe the answer is:

many a one

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

'lots of people' is the definition.

'made quite a few singles' is the wordplay.
I cannot quite understand how this works, but
'a' could be 'one' and 'one' is found in the answer.
The remaining letters 'manya' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).

'have' acts as a link.

Can you help me to learn more?

I've seen this clue in the Evening Standard.

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