Pass through taking in Sweden's capital (4)
I believe the answer is:
visa
'pass' is the definition.
(pass allowing international travel)
'through taking in sweden's capital' is the wordplay.
'through' becomes 'via' (I've seen this in another clue).
'taking in' means one lot of letters goes inside another.
'capital' indicates taking the first letters.
The initial letter of 'sweden' is 's'.
'via' going around 's' is 'VISA'.
(Other definitions for visa that I've seen before include "giving you access to capital?" , "ID" , "Stamp affixed to passport as permission to enter country" , "Travel document is required to enter Virginia" , "Travel pass" .)