Ship's bunk (5)
I believe the answer is:
berth
'ship's bunk' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for berth that I've seen before include "Bunk on ship or train" , "Place to lie down on train or ship" , "Sleeping place in ship" , "Place to sleep on a ship" , "Bed; mooring" .)