Being sold very cheaply (5,3,1,4)
I believe the answer is:
going for a song
'being sold very cheaply' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for going for a song that I've seen before include "Being sold very cheaply" , "Being offered very cheaply" , "Available at a bargain price" , "Available very cheap" , "Selling very cheaply" .)