Playwright (female) at rock bottom after upset (8)
I believe the answer is:
sheridan
'playwright' is the definition.
(I know that Sheridan is a playwright)
'female at rock bottom after upset' is the wordplay.
'female' becomes 'she' ('she' refers to a woman).
'at' means one lot of letters go next to another.
'rock bottom' becomes 'nadir' (a nadir is something's lowest point).
'after upset' is a reversal indicator (in a down clue, letters go up).
'nadir' written backwards gives 'ridan'.
'she'+'ridan'='SHERIDAN'
(Other definitions for sheridan that I've seen before include "Creator of Mrs Malaprop in The Rivals" , "Richard Brinsley . . . . . . . . was a great 18th century Irish playwright" , "School for Scandal playwright" , "Richard Brinsley ........, Anglo-Irish author of ` `The School for Scandal' '" , "Irish dramatist" .)