Playwright was a tot at first (9)
I believe the answer is:
dramatist
'playwright' is the definition.
(I know that playwright can be written as dramatist)
'a tot at first' is the wordplay.
'a tot' becomes 'dram' (I've seen this in another clue).
'first' becomes 'ist' (ist resembles 1st).
'dram'+'at'+'ist'='DRAMATIST'
'was' acts as a link.
(Other definitions for dramatist that I've seen before include "Shakespeare, say" , "Coward perhaps" , "Pinter, say" , "O'Neill or O'Casey, for example" , "Writer of plays" .)