Set free anaemic pet after treatment (10)
I believe the answer is:
emancipate
'set free' is the definition.
(emancipating is a kind of setting free)
'anaemic pet after treatment' is the wordplay.
'after treatment' indicates an anagram.
'anaemic'+'pet'='anaemicpet'
'anaemicpet' with letters rearranged gives 'EMANCIPATE'.
(Other definitions for emancipate that I've seen before include "Free from slavery" , "Liberate" , "Set free" , "Free from restrictions" , "setting free" .)