Not now the capital of Norway (4)
I believe the answer is:
then
'not now' is the definition.
(I've seen this in another clue)
'the capital of norway' is the wordplay.
'capital of' suggests taking the first letters.
The first letter of 'norway' is 'n'.
'the'+'n'='THEN'
(Other definitions for then that I've seen before include "Consequently" , "Subsequently - previously" , "At that time; next" , "Afterwards - as a result" , "soon?" .)