Not all regular guests bicker (5)
I believe the answer is:
argue
'bicker' is the definition.
(I've seen this before)
'not all regular guests' is the wordplay.
'not all' indicates a hidden word (only some of the letters).
'ARGUE' is hidden in the letters of 'regular guests'.
(Other definitions for argue that I've seen before include "Present reasons for or against" , "Make a case" , "Debate, contest verbally" , "Heatedly exchange views" , "Quarrel or disagree" .)