A right angry tirade, out-and-out (6)
I believe the answer is:
arrant
'out-and-out' is the definition.
('arrant' can be a synonym of 'out-and-out')
'a right angry tirade' is the wordplay.
'a right' becomes 'ar' (I've seen this in other clues).
'angry tirade' becomes 'rant' (I've seen this before).
'ar'+'rant'='ARRANT'
(Other definitions for arrant that I've seen before include "Downright, out and out like nonsense" , "Rat ran badly and became unmitigated" , "Blatant" , "Downright, out-and-out - say nonsense" , "Out-and-out, downright - often nonsense" .)