Cairo's river (4)
I believe the answer is:
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">cairo's river</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 nile that I've seen before include "White or Blue river of Africa" , "Cleopatra's river" , "Cairo's river" , "River of Egypt" , "white flower?" .)