Release songs for performance without payment (3,4)
I believe the answer is:
set free
'release' is the definition.
(synonyms)
'songs for performance without payment' is the wordplay.
'songs for performance' becomes 'set' (as in a set list for a concert).
'without payment' becomes 'free' (free of charge).
'set'+'free'='SET FREE'
(Other definitions for set free that I've seen before include "Released" , "no longer detained" , "without the box" , "Uncaged birds have been" , "Liberate" .)