Bid adieu
I believe the answer is:
leave
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">bid adieu</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 leave that I've seen before include "Deposit" , "Go - on holidays?" , "Skip" , "Permission to take a vacation" , "Clearance" .)