So upset, tolerated British dramatist (7)
I believe the answer is:
osborne
'british dramatist' is the definition.
(I know this)
'so upset tolerated' is the wordplay.
'upset' is a reversal indicator.
'tolerated' becomes 'borne' (I've seen this in another clue).
'so' reversed gives 'os'.
'os'+'borne'='OSBORNE'
(Other definitions for osborne that I've seen before include "John -, playwright (Look Back in Anger)" , "grand island house" , "Politician" , "John --, English dramatist" , "Look Back in Anger writer" .)