What the following numbers show (10)

I think it could be either:

Which length description are you looking for?:

4,6

wordlength

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'what the following numbers' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.

'show' is the wordplay.
I cannot quite see how this works, but
'show' could be 'word' (wording is a kind of showing) and 'word' is found in the answer.
The remaining letters 'length' is a valid word which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).

Can you help me to learn more?

I've seen this clue in The Guardian.

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