Vessel carrying article to north island (4)
I believe the answer is:
guam
'island' is the definition.
(Guam is an example)
'vessel carrying article to north' is the wordplay.
'vessel' becomes 'mug' (mug is a kind of vessel).
'carrying' indicates putting letters inside.
'article' becomes 'a' (indefinite article).
'to north' shows that the letters should be reversed in order (in a down clue, letters go up or 'northward').
'mug' placed around 'a' is 'maug'.
'maug' back-to-front is 'GUAM'.
(Other definitions for guam that I've seen before include "North Pacific island, base for the US navy and air force" , "Largest of the Mariana Islands" , "NW Pacific island with large US base" , "US unincorporated territory in the western Pacific" , "place in the Marianas" .)