Fool repeatedly at home for killer (8)
I believe the answer is:
assassin
'killer' is the definition.
(I know that killer can be written as assassin)
'fool repeatedly at home for' is the wordplay.
'fool repeatedly' means two substitutions for 'fool'.
'fool' becomes 'ass' (both can mean a stupid person).
'fool' becomes 'ass' (both can mean a stupid person).
'at' becomes 'in' (synonymous in some cases - eg at school, in school).
'home for' is an insertion indicator (inserted letters are homed by others).
'ass'+'in'='assin'
'ass' inserted inside 'assin' is 'ASSASSIN'.
(Other definitions for assassin that I've seen before include "Bravo!" , "Murderer (of prominent figure)" , "Killer of famous person" , "butcher" , "Hired murderer" .)