Criminal behaviour having one in gang shot (8)
I believe the answer is:
banditry
'criminal behaviour' is the definition.
(I've seen this before)
'one in gang shot' is the wordplay.
'one' becomes 'i' (Roman numeral).
'in' means one lot of letters goes inside another.
'gang' becomes 'band' (both can mean a group of people).
'shot' becomes 'try' (both can mean an attempt).
'band'+'try'='bandtry'
'i' put into 'bandtry' is 'BANDITRY'.
'having' is the link.
(Other definitions for banditry that I've seen before include "Brigandage" , "Criminal behaviour" , "Activity of lawless robbers" , "Outlawry" , "Plundering in gangs" .)