He let Peron become a ringer (10)

I believe the answer is:

telephoner

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

'a ringer' is the definition.
The definition and answer can be both people as well as being singular nouns.
Perhaps there's an association between them I don't understand?

'he let peron become' is the wordplay.
'become' indicates an anagram.
'he'+'let'+'peron'='heletperon'
'heletperon' with letters rearranged gives 'TELEPHONER'.

Can you help me to learn more?

I've seen this clue in the Sydney Morning Herald.

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