Mad artist converted to playwright (9)
I believe the answer is:
dramatist
'playwright' is the definition.
('dramatist' can be a synonym of 'playwright')
'mad artist converted' is the wordplay.
'converted' indicates an anagram.
'mad'+'artist'='madartist'
'madartist' anagrammed gives 'DRAMATIST'.
'to' is the link.
(Other definitions for dramatist that I've seen before include "Writer of plays" , "One who writes plays" , "O'Neill or O'Casey, for example" , "Shakespeare, say" , "Wordsmith" .)