Outrageous tirade after standard’s shown (8)
I believe the answer is:
flagrant
'outrageous' is the definition.
(flagrant can mean outrageous or blatant)
'tirade after standard's shown' is the wordplay.
'tirade' becomes 'rant' (both can mean an angry outburst).
'after' is a charade indicator (letters next to each other).
'standard's shown' becomes 'flag' (I can't justify this - if you can you should give a lot more credence to this answer).
'rant' put after 'flag' is 'FLAGRANT'.
(Other definitions for flagrant that I've seen before include "Shocking" , "Being shameless" , "Very bad and obvious, say offence" , "Barefaced" , "Unashamed" .)