Philosopher Wittgenstein (6)
I believe the answer is:
ludwig
'philosopher wittgenstein' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for ludwig that I've seen before include "Wagner's kingly patron" , "Mad Bavarian king" , "Name shared by Beethoven, Wittgenstein" , "Mad king of Bavaria" , "Perhaps Beethoven" .)