What Hitler was entitled to be called (4)
I believe the answer is:
herr
I'm afraid I can't even guess how this answer relates to the clue.
Can you help me to learn more?
(Other definitions for herr that I've seen before include "Mister in German" , "Dieter respectfully addressed" , "German man's title" , "European guy" , "Form of address for German male" .)