It doesn’t cost a dime, darling (4,4)
I believe the answer is:
free love
'it doesn't cost a dime darling' is the definition.
The definition suggests a singular noun which matches the answer.
This is the entire clue.
Can you help me to learn more?
(Other definitions for free love that I've seen before include "General Congress" , "Promiscuity" , "presumably ruling out bondage" .)