Public school pupil (7)
I believe the answer is:
etonian
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">public school pupil</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 etonian that I've seen before include "Public schoolboy" , "English student" , "Relating to one particular school" , "Public school boy" , "student in establishment?" .)