Ship's canvas (4)
I believe the answer is:
sail
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">ship's canvas</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 sail that I've seen before include "Put to sea in yacht" , "Fabric on a mast" , "Canvas sheet" , "Go by water" , "Begin a voyage" .)