Individual is firm about dramatist (7)
I believe the answer is:
ionesco
'dramatist' is the definition.
(I know that Ionesco is a dramatist)
'individual is firm about' is the wordplay.
'individual' becomes 'one' (an individual is one person).
'firm' becomes 'co' (a firm is a company).
'about' means one lot of letters goes inside another.
'is'+'co'='isco'
'one' put into 'isco' is 'IONESCO'.
(Other definitions for ionesco that I've seen before include "Eugene -, Fr. dramatist (Theatre of the Absurd)" , "French dramatist, leading figure in the theatre of the absurd, d. 1994" , "Absurdist playwright" , "O so nice (anag) - playwright" , "Playwright associated with the theatre of the absurd" .)