Go by boat (4)
I believe the answer is:
sail
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">go by boat</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for sail that I've seen before include "Canvas sheet" , "Travel by boat" , "project" , "Put to sea in yacht" , "Canvas on board" .)