With which one buys something bought for a song? (5)
I believe the answer is:
notes
I'm afraid I can't even guess how this answer relates to the clue.
Can you help me to learn more?
(Other definitions for notes that I've seen before include "Doh, re, mi, ..." , "Memos; marks" , "Short missives" , "fivers?" , "Short written messages" .)