Captain's place on a ship (4)
I believe the answer is:
'captain's place on a ship' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for helm that I've seen before include "Ship's steering apparatus" , "Tiller - part of armour" , "Wheel that controls ship's rudder" , "Steering device" , "Steering mechanism" .)