Moonwalker Shepard (4)
I believe the answer is:
alan
'moonwalker shepard' 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 "Sir -- Sugar (The Apprentice)" , "-- Ayckbourn, English dramatist" , "-- Bennett, playwright" , "English historian/poet" , "- Bennett, English actor, dramatist, writer" .)