Swedish port, but it's in Vietnam, almost! (5)
I believe the answer is:
malmo
'swedish port' is the definition.
(I've seen this in another clue)
'it's in vietnam almost' is the wordplay.
'it's in' indicates a hidden word.
'MALMO' is hidden in the letters of 'vietnam almost'.
'but' is the link.
(Other definitions for malmo that I've seen before include "city in Sweden" , "Swedish city and port" .)