School class (4)
I believe the answer is:
form
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">school class</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 form that I've seen before include "Criminal record (colloq.)" , "Home of a hare" , "Seat" , "Class; schedule" , "Acceptable conduct" .)