Norwegian capital in Czechoslovakia (4)
I believe the answer is:
oslo
'norwegian capital' is the definition.
(capital of Norway)
'in czechoslovakia' is the wordplay.
'in' indicates the answer is hidden within the clue.
'OSLO' can be found hidden inside 'czechoslovakia'.
(Other definitions for oslo that I've seen before include "European capital city (found in Czechoslovakia!)" , "Capital of Norway" , "It's capital in Anglos London" , "Nordic capital" , "European capital in go-slow" .)