Only half a house? (4)
I believe the answer is:
semi
I believe this is a double definition.
'only half' is the first definition.
(I've seen this in another clue)
'a house?' is the second definition.
(short for semi-detached)
(Other definitions for semi that I've seen before include "Prefix denoting half" , "Residence" , "The last but one round" , "House sharing a wall" , "House attached to one other" .)