Hospitality for all in old luxury flat as temperature falls (4,5)

I believe the answer is:

open house

'hospitality for all' is the definition.
(hospitality for all visitors)

I don't understand how the rest of the clue works.

(Other definitions for open house that I've seen before include "Total hospitality" , "welcoming situation" , "Informal party with hospitality for all comers" , "Unrestricted hospitality" , "unbounded hospitality" .)

I've seen this clue in The Times.

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