World capital on a fjord (4)
I believe the answer is:
oslo
'world capital on a fjord' 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 "Capital city, called Kristiania until 1924" , "Go solo to European capital" , "Nordic city" , "foreign port" , "Scandinavian port" .)