Mob area's got gangs, occasionally (6)
I believe the answer is:
ragtag
'mob' is the definition.
(I've seen this before)
'area's got gangs occasionally' is the wordplay.
'occasionally' indicates alternate letters (letters taken at regular intervals or occasions).
'areas'+'got'+'gangs'='areasgotgangs'
The alternating letters of 'areasgotgangs' are 'RAGTAG'.
(Other definitions for ragtag that I've seen before include "Common people, riff-raff - ...... and bobtail" , "Untidy, disorganised" , "Masses" , ". . . . . . and bobtail, the rabble" , "Mob" .)