Regularly indulged in lounge (4)
I believe the answer is:
idle
'in lounge' is the definition.
(I've seen this before)
'regularly indulged' is the wordplay.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
The alternate letters of 'indulged' are 'IDLE'.
(Other definitions for idle that I've seen before include "without basis" , "'Lazy, not doing anything (4)'" , "lndolent" , "without purpose" , "Avoiding work, lazy" .)