Uproar caused by American chasing tail (6)
I believe the answer is:
rumpus
'uproar' is the definition.
(thesaurus)
'american chasing tail' is the wordplay.
'american' becomes 'us'.
'chasing' says to put letters next to each other.
'tail' becomes 'rump' ('rump' can be a synonym of 'tail'**).
'us' after 'rump' is 'RUMPUS'.
'caused by' acts as a link.
(Other definitions for rumpus that I've seen before include "Noisy disturbance" , "Tumult" , "To-do" , "Harsh rough nature" , "Kerfuffle" .)