Nobel Peace Prize city (4)
I believe the answer is:
oslo
'nobel peace prize city' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for oslo that I've seen before include "European capital, known until 1924 as Christiania" , "Former Christiania" , "Scandinavian port" , "Capital in throes of go-slow" , "European capital city (found in Czechoslovakia!)" .)