Left harbour (4)
I believe the answer is:
port
I believe this is a double definition.
'left' is the first definition.
(left side of a ship - opposite of starboard)
'harbour' is the second definition.
(I've seen this before)
(Other definitions for port that I've seen before include "Isle in Dorset" , "Harbour; alcoholic drink" , "E.g. five [SWANSEA]" , "'Any . . . . In a storm'" , "Dessert wine" .)