"Heyo" (3)
I believe the answer is:
sup
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">heyo</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 sup that I've seen before include "Eat a late meal; sip" , "Imbibe" , "A mouthful of liquid" , "Drink; take a late meal" , "Drink; take an evening meal" .)