House not full? (4)

I believe the answer is:

semi

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'house' is the definition.
(semi-detached house)

I don't understand the rest of the clue.

(Other definitions for semi that I've seen before include "accommodation" , "Dwelling" , "Residence" , "Partly detached home" , "important match" .)

I've seen this clue in the Evening Standard.

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