Letter after beta (5)
I believe the answer is:
gamma
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">letter after beta</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 gamma that I've seen before include "The Greek g, third in alphabet" , "Poor mark" , "third highest grade" , "A bit of Greek" , "Third class, Gk. letter" .)