Destroyed anaemic pet for free (10)
I believe the answer is:
emancipate
'free' is the definition.
(thesaurus)
'destroyed anaemic pet' is the wordplay.
'destroyed' indicates an anagram.
'anaemic'+'pet'='anaemicpet'
'anaemicpet' anagrammed gives 'EMANCIPATE'.
'for' is the link.
(Other definitions for emancipate that I've seen before include "Free from slavery" , "release" , "Set free" , "Free from restrictions" , "Liberate" .)