Uppermost point (3)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">uppermost point</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 apex that I've seen before include "Apogee, summit" , "Peak, vertex" , "Uppermost point" , "Point or summit" , "The highest point or peak" .)
(Other definitions for top that I've seen before include "Peak; beat" , "Zenith" , "Spinner" , "Apex; child's toy" , "Kill" .)