Understood to have dropped case in (2,4)

I believe the answer is:

at home

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'in' is the definition.
(someone at home is 'in')

I cannot understand how the remainder of the clue works.

(Other definitions for at home that I've seen before include "Reception in one's own abode" , "In one's own house" , "celebration" , "Where one lives" , "Comfortable - in one's own country" .)

I've seen this clue in The Times.

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