Scam inside Las Vegas ends in confusion (4)
I believe the answer is:
mess
'confusion' is the definition.
(mess can mean confusion or chaos)
'scam inside las vegas ends' is the wordplay.
'ends' suggests the final letters.
The final letters of 'scam inside las vegas' are 'MESS'.
'in' is the link.
(Other definitions for mess that I've seen before include "Officers' restaurant - what a dump" , "Jumble" , "Dirty or untidy state" , "pickle" , "Where those who serve eat" .)