Criminal activity in bar: detective shot (8)
I believe the answer is:
banditry
'criminal activity' is the definition.
(I've seen this before)
'bar detective shot' is the wordplay.
'bar' becomes 'ban' (bar can mean to ban or prohibit).
'detective' becomes 'di' (Detective Inspector abbreviation).
'shot' becomes 'try' (both can mean an attempt).
'ban'+'di'+'try'='BANDITRY'
'in' is the link.
(Other definitions for banditry that I've seen before include "robbery" , "Criminal behaviour" , "Plundering in gangs" , "Activity of violent robbers" , "Activity of lawless robbers" .)