What they called Hitler before the war (4)

I believe the answer is:
herr
'war' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how they can define each other.
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for herr that I've seen before include "European guy" , "Mister in German" , "Dieter respectfully addressed" , "German man's title" , "Form of address for German male" .)
