End of the Greek alphabet (5)
I believe the answer is:
omega
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">end of the greek alphabet</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 omega that I've seen before include ""The Alpha and the ___"" , "end of series" , "16 letter" , "Conclusion" , "Ultimate letter" .)