It's left on a boat (4)
I believe the answer is:
port
'it's left on a boat' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for port that I've seen before include "After-dinner wine" , "Wine - left - harbour" , "Alcoholic drink after meal or sea shelter" , "Harbour; drink; opening" , "Anchorage" .)