Turing who helped crack the Enigma code (4)

I believe the answer is:

alan

(Other definitions for alan that I've seen before include "English historian/poet" , "Boy's name" , "Messrs Ladd and Dukes" , "-- Sugar, British entrepreneur" , "-- Turing, mathematician" .)

I've seen this clue in the Universal.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.