Last Greek letter (5)
I believe the answer is:
omega
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">last greek letter</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 omega that I've seen before include "end of series" , "character in Greek literature?" , "End of sequence" , "Final Greek letter" , "Athenian character" .)