Hit man when given cheek at home (8)
I believe the answer is:
assassin
'hit man' is the definition.
(thesaurus)
'when given cheek at home' is the wordplay.
'when' becomes 'as'.
'given' says to put letters next to each other.
'cheek' becomes 'sass' (sass is a kind of cheek**).
'at home' becomes 'in' ('in' can be similar in meaning to 'at home').
'as'+'sass'+'in'='ASSASSIN'
(Other definitions for assassin that I've seen before include "Carlos the Jackal was one" , "Booth, for example" , "Hired killer" , "One murders for political or monetary reasons" , "Paid killer" .)