Vigilantes having semi? (5)
I believe the answer is:
posse
This clue might be a double definition.
'vigilantes' is the first definition.
(thesaurus)
'semi?' is the second definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'having' acts as a link.
Can you help me to learn more?
(Other definitions for posse that I've seen before include "Group of sheriff's men" , "Body of constables" , "Law-enforcers" , "Band supporting sheriff" , "Sheriff's party" .)