Disreputable bunch regularly goes bananas (6,7)
I believe the answer is:
rogues gallery
'disreputable bunch' is the definition.
(group of disreputable characters)
'regularly goes bananas' is the wordplay.
'bananas' indicates anagramming the letters (informal term for mad).
'regularly'+'goes'='regularlygoes'
'regularlygoes' is an anagram of 'ROGUES' GALLERY'.
(Other definitions for rogues gallery that I've seen before include "Collection of pictures of criminals" , "collection of mugshots" , "Set of criminals' photos" , "Mug collection" , "Group of undesirables" .)