Former German kingdom (7)
I believe the answer is:
prussia
'former german kingdom' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for prussia that I've seen before include "Former state that included present-day Northern Germany and northern Poland" , "Former kingdom, included northern Germany and northern Poland" , "Old European state" , "Former German kingdom" , "Bismarck its PM" .)