Towards the stern (3)
I believe the answer is:
aft
'towards the stern' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for aft that I've seen before include "Towards rear (of ship)" , "behind at sea" , "Towards the rear at sea" , "Toward's a ship's stern" , "Toward the stern of a boat" .)