Upset crime scene extends across house (4)
I believe the answer is:
semi
'house' is the definition.
(short for semi-detached)
'upset crime scene extends across' is the wordplay.
'upset' says the letters should be written in reverse.
'across' indicates the answer is hidden within the clue.
'imes' is hidden within 'crime scene extends'.
'imes' reversed gives 'SEMI'.
(Other definitions for semi that I've seen before include "House sharing a wall" , "Prefix meaning half (4)" , "Half (pfx)" , "Co-joined house" , "One house of pair" .)