Bedlam as Charles banks zero (5)
I believe the answer is:
chaos
'bedlam' is the definition.
(I know that bedlam can be written as chaos)
'charles banks zero' is the wordplay.
'charles' becomes 'Chas' (shortened form).
'banks' indicates putting letters inside (bank can mean to surround or border).
'zero' becomes 'O' (O resembles 0).
'chas' placed around 'o' is 'CHAOS'.
'as' acts as a link.
(Other definitions for chaos that I've seen before include "Absence of order" , "Anarchy" , "confused state" , "disarray" , "upheaval" .)