Alpha's follower (4)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">alpha's follower</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 beta that I've seen before include "sort of test" , "Second letter of the Greek alphabet" , "Second highest grade of mark" , "Second-rate" , "It's next after alpha" .)