Upset endlessly richer German state (5)
I believe the answer is:
reich
'german state' is the definition.
(as in the Third Reich)
'upset endlessly richer' is the wordplay.
'upset' indicates anagramming the letters.
'endlessly' means to remove the last letter.
'richer' with its last letter taken away is 'riche'.
'riche' is an anagram of 'REICH'.
(Other definitions for reich that I've seen before include "Hitler's was the Third" , "Old German state" , "Former German state - the Nazi era was the Third" , "Nazi empire" , "kingdom" .)