Nautical steering device (6)
I believe the answer is:
rudder
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">nautical steering device</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for rudder that I've seen before include "It is used to steer boat or plane" , "It guides" , "Ship's steerer" , "Boat's steering device" , "Helm" .)