Refuse to kill American, a Liberal (5)
I believe the answer is:
offal
'refuse' is the definition.
(thesaurus)
'kill american a liberal' is the wordplay.
'kill' becomes 'off' ('off' can informally mean 'murder'**).
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'a liberal' becomes 'l' (abbreviation).
'off'+'a'+'l'='OFFAL'
'to' is the link.
(Other definitions for offal that I've seen before include "Liver, lights, etc" , "Edible (or inedible!) animal organs" , "Butcher's leftovers" , "Edible heart, liver and tongue, for instance" , "Putting cargo on (ship)" .)