A gang operating in ditch (7)
I believe the answer is:
abandon
'ditch' is the definition.
(thesaurus)
'a gang operating' is the wordplay.
'gang' becomes 'band' (I've seen this before).
'operating' becomes 'on' (I've seen this in other clues).
'a'+'band'+'on'='ABANDON'
'in' acts as a link.
(Other definitions for abandon that I've seen before include "Leave in the lurch" , "Lack of constraint" , "Cast aside" , "ditch" , "Leave (a place) for ever" .)