"Hamilton" showdown (4)
I believe the answer is:
duel
'hamilton showdown' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for duel that I've seen before include "Gentlemen's disagreement" , "Potentially fatal fight between two people" , "Two-person combat" , "Combat between two people in matter of honour" , "Combat to settle a row" .)