Heard one much admired is not working (4)
I believe the answer is:
idle
'is not working' is the definition.
(idle means doing no work)
'heard one much admired' is the wordplay.
'heard' indicates a 'sounds like' (homophone) clue.
'one much admired' becomes 'idol' (I've seen this before).
'idol' is a homophone of 'IDLE'.
(Other definitions for idle that I've seen before include "Avoiding work, lazy" , "Do nothing, laze" , "Ineffectual" , "staying in bed all day?" , "Not busy" .)