A single short song going out to listeners (2,3)
I believe the answer is:
on air
'going out to listeners' is the definition.
I don't know anything about this answer so I cannot tell whether this works.
'a single short song' is the wordplay.
'a single' becomes 'one' (a single thing - only one).
'short' means to remove the last letter.
'song' becomes 'air' (air can mean a piece of music).
'one' with its final letter removed is 'on'.
'on'+'air'='ON-AIR'
Can you help me to learn more?
(Other definitions for on air that I've seen before include "Broadcasting studio sign" , "In the act of broadcasting" , "In the process of broadcasting - floating aloft?" , "Walk in delight here" , "Broadcasting live" .)