Commonly quit humbug (4)
I believe the answer is:
bunk
'humbug' is the definition.
(thesaurus)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for bunk that I've seen before include "Type of bed" , "A tiered bed" , "Rubbish - place to sleep" , "Somewhere to sleep" , "History (said Henry Ford) - bed!" .)