Pursuit group in westerns (5)
I believe the answer is:
posse
'pursuit group in westerns' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for posse that I've seen before include "Gang" , "Group of friends together" , "Sheriff's party" , "Troop at the service of a local sheriff" , "Law-enforcers" .)