Murder -- one group of detectives seen in house (8)
I believe the answer is:
homicide
'murder' is the definition.
('homicide' can be a synonym of 'murder')
'one group of detectives seen in house' is the wordplay.
'one group of' becomes 'i' (I've seen this in other clues).
'detectives' becomes 'cid'.
'seen in' means one lot of letters goes inside another.
'house' becomes 'home' (homing is a kind of housing).
'i'+'cid'='icid'
'icid' inserted within 'home' is 'HOMICIDE'.
(Other definitions for homicide that I've seen before include "Unlawful killing of a person by another" , "The killing of one human by another" , "Murder (of one person)" , "The killing of one person by another" , "Manslaughter or murder" .)