Mister, in Münster (4)
I believe the answer is:
herr
'mister in munster' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for herr that I've seen before include "German form like Mr." , "A German gentleman" , "German man's title" , "Dieter respectfully addressed" , "Mister in German" .)