Second letter of the Greek alphabet (4)
I believe the answer is:
beta
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">second letter of the greek alphabet</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 beta that I've seen before include "Character between alpha and gamma" , "Second Greek letter - beat that" , "2nd letter of Greek alphabet" , "Second Greek letter, B" , "software under test" .)