Convention center event (4)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">convention center event</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for expo that I've seen before include "Public exhibition" , "public display" , "Large international exhibition" , "Public spectacle" , "World fair, e.g. Seville 1992" .)