Being the last element of a series (8)
I believe the answer is:
ultimate
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">being the last element of a series</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for ultimate that I've seen before include "Happening at the end of a process, final" , "Eventual" , "Last or final in a series or process" , "Utmost or extreme" , "Happening last" .)