Famous girls' school (7)
I believe the answer is:
roedean
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">famous girls' school</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 roedean that I've seen before include "Brighton girls' school" , "Famous girls' school" , "Posh girls' school in Sussex" , "Independent school" , "Girls public school" .)