Playwright Ayckbourn (4)
I believe the answer is:
'playwright ayckbourn' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for alan that I've seen before include "A.A. Milne's first name" , "Boy" , "English historian/poet" , "Sir -- Sugar (The Apprentice)" , "Messrs Ladd and Dukes" .)