Release a collection of songs at no cost (3,4)
I believe the answer is:
set free
'release' is the definition.
(synonyms)
'a collection of songs at no cost' is the wordplay.
I cannot really see how this works, but
'collection' could be 'set' (set is a kind of collection) and 'set' is found in the answer.
'no cost' could be 'free' (I've seen this in other clues) and 'free' is found in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for set free that I've seen before include "Release, remove restraints" , "Liberate" , "no longer confined" , "Deliver - release" , "Clear" .)