Meal for four? (9,3)

I believe the answer is:

afternoon tea

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

This might be a double definition.

'meal' is the first definition.
(afternoon tea is a kind of meal)

'four?' is the second definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.

'for' is the link.

Can you help me to learn more?

(Another definition for afternoon tea that I've seen is " Polite snack?".)

I've seen this clue in The Guardian.

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