Half a house? (4)
I believe the answer is:
semi
This clue is a double definition.
'half' is the first definition.
(I've seen this before)
'a house' is the second definition.
(short for semi-detached)
(Other definitions for semi that I've seen before include "home perhaps" , "Style of house" , "Type of house (UK) - type of truck (US)" , "Prefix denoting half" , "match, the last but one?" .)