Endless sea mist engulfing vehicle in foreign port (6)
I believe the answer is:
havana
'foreign port' is the definition.
(port in Cuba)
'endless sea mist engulfing vehicle' is the wordplay.
'endless' means to remove the last letter.
'sea mist' becomes 'haar' (I've seen this before).
'engulfing' is an insertion indicator.
'vehicle' becomes 'van' (type of vehicle).
'haar' with its last letter taken off is 'haa'.
'haa' placed around 'van' is 'HAVANA'.
'in' acts as a link.
(Other definitions for havana that I've seen before include "lit up in celebration" , "city" , "Cuban capital - cigar" , "island capital" , "Smoke" .)