Group of undesirables regularly goes abroad (6,7)
I believe the answer is:
rogues gallery
'group of undesirables' is the definition.
(I've seen this before)
'regularly goes abroad' is the wordplay.
'abroad' indicates an anagram.
'regularly'+'goes'='regularlygoes'
'regularlygoes' is an anagram of 'ROGUES' GALLERY'.
(Other definitions for rogues gallery that I've seen before include "Portraits of criminals" , "Collection of photographs of known criminals" , "Collection of pictures of criminals" , "Collection of undesirables" , "Criminal line-up" .)