About to argue, upset in dice game (5)
I believe the answer is:
craps
'dice game' is the definition.
(I've seen this in another clue)
'about to argue upset' is the wordplay.
'about' becomes 'c' (circa).
'to argue' becomes 'spar' (sparring is a kind of arguing).
'upset' says the letters should be written in reverse.
'spar' in reverse letter order is 'raps'.
'c'+'raps'='CRAPS'
'in' acts as a link.
(Other definitions for craps that I've seen before include "2 8 [CASINO GAMES]" , "Gambling game involving dice" , "[EXCRETA]" .)