Former students (6)
I believe the answer is:
alumni
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">former students</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 alumni that I've seen before include "Ex-students" , "Graduates of a college" , "we studied at a certain place" , "Former (college) students" , "Put too much strain on, as Revenue Commissioners do" .)