Narrow shelf-like bed (4)
I believe the answer is:
bunk
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">narrow shelf-like bed</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for bunk that I've seen before include "Bed on board" , "History, according to Ford" , "Somewhere to sleep" , "Narrow shelf-like bed" , "Rubbish - place to sleep" .)