Insisting that you tell them all again (9,1,7)

I believe the answer is:

demanding a recount

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

'insisting that you' is the definition.
I don't know anything about this answer so I cannot tell whether this works.

'tell them all again' is the wordplay.
I cannot really understand how this works, but
'tell' could be 'recount' (synonyms) and 'recount' is found in the answer.
'them' could be 'em' (abbreviation) and 'em' is found in the answer.
This explanation may well be incorrect...

Can you help me to learn more?

I've seen this clue in the Evening Standard.

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