House half a mile to the southeast (4)
I believe the answer is:
semi
'house' is the definition.
(short for semi-detached)
'half a mile to the southeast' is the wordplay.
'half a' suggests halving the letters.
'to' is a charade indicator (letters next to each other) (I've seen this in other clues).
'the southeast' becomes 'SE' (synonyms).
'mile' cut in half is 'mi'.
'mi' after 'se' is 'SEMI'.
(Other definitions for semi that I've seen before include "Half (pfx)" , "The next to final round" , "Articulated lorry (US)" , "Property attached to another" , "Partly detached home" .)