Independent detectives gripped by domestic killing (8)
I believe the answer is:
homicide
'killing' is the definition.
(homicide is a kind of killing)
'independent detectives gripped by domestic' is the wordplay.
'independent' becomes 'i'.
'detectives' becomes 'cid'.
'gripped by' is an insertion indicator.
'domestic' becomes 'home' ('home' can be similar in meaning to 'domestic').
'i'+'cid'='icid'
'icid' put within 'home' is 'HOMICIDE'.
(Other definitions for homicide that I've seen before include "Murder (of one person)" , "Murder (mainly US)" , "The killing of one person by another" , "Unlawful killing of a person by another" , "The killing of one human by another" .)