Says yes to acquiring assembly room for a feast day (3,7)

I believe the answer is:

all-hallows

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

'a feast day' is the definition.
(I've seen this before)

'says yes to acquiring assembly room' is the wordplay.
'says yes' becomes 'allows' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'to acquiring' means one lot of letters goes inside another.
'assembly room' becomes 'hall'.
'allows' placed around 'hall' is 'ALL-HALLOWS'.

'for' is the link.

Can you help me to learn more?

I've seen this clue in The Telegraph.

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