Ruhr city (5)
I believe the answer is:
essen
'ruhr city' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for essen that I've seen before include "city in the Ruhr valley" , "European city" , "Industrial city of northwest Germany" , "German industrial city on the Ruhr" , "German place name" .)