Liberated collection at no charge (3,4)
I believe the answer is:
set free
'liberated' is the definition.
(I've seen this in another clue)
'collection at no charge' is the wordplay.
'collection' becomes 'set' (set is a kind of collection).
'at no charge' becomes 'free' (I've seen this in another clue).
'set'+'free'='SET FREE'
(Other definitions for set free that I've seen before include "Turn loose" , "no longer confined" , "Uncaged birds have been" , "Deliver - release" , "no longer detained" .)