Helmsman's direction to port (4)
I believe the answer is:
left
This clue could be a double definition.
'helmsman's direction' is the first definition.
'left' can be an answer for 'direction' (I have seen 'Socialist direction' mean 'left' so perhaps 'direction' could also mean 'left'). I am unsure of the 'helmsman's' bit.
'to port' is the second definition.
(port is the left side on a boat)
Can you help me to learn more?
(Other definitions for left that I've seen before include "not consumed" , "political grouping" , "Facing north, it's the side toward the west" , "Departed, went away" , "split" .)