Uproar in America after 'The Chosen One' loses his head (6)
I believe the answer is:
rumpus
'uproar' is the definition.
(I've seen this before)
'america after the chosen one loses his head' is the wordplay.
'america' becomes 'us' (abbreviation for the United States).
'after' says to put letters next to each other.
'the chosen one' becomes 'trump' (Donald Trump called himself The Chosen One).
'loses his head' means to remove the first letter.
'trump' with its initial letter removed is 'rump'.
'us' put after 'rump' is 'RUMPUS'.
'in' is the link.
(Other definitions for rumpus that I've seen before include "Noisy, disruptive commotion" , "To-do" , "Noisy brawl" , "Noisy disturbance" , "Kerfuffle" .)