Lounge in which hero can be heard (4)
I believe the answer is:
idle
'lounge' is the definition.
(I've seen this in another clue)
'hero can be heard' is the wordplay.
'hero' becomes 'idol' (I've seen this in another clue).
'can be heard' indicates a 'sounds like' (homophone) clue.
'idol' is a homophone of 'IDLE'.
'in which' is the link.
(Other definitions for idle that I've seen before include "no longer employed?" , "having been taken from service" , "goalless" , "Futile" , "Not in action or at work" .)