Go aboard (6)
I believe the answer is:
embark
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">go aboard</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for embark that I've seen before include "get on board" , "Start" , "Set out on journey" , "Put to sea" , "Go on board ship or plane" .)