Hundredth anniversary (9)
I believe the answer is:
centenary
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">hundredth anniversary</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for centenary that I've seen before include "special occasion" , "celebration" , "One hundredth anniversary" , "... so celebrating this next month" , "significant anniversary" .)