First Greek letter (5)
I believe the answer is:
alpha
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">first greek letter</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 alpha that I've seen before include "letter written in Greek" , "First letter of the Greek alphabet" , "Early testing stage for new software or hardware" , "Foremost" , "First (class)" .)