The highest point (4)
(Other definitions for acme that I've seen before include "Summit of achievement" , "crown" , "Highest stage of development" , "Culminating point" , "Summit - zenith" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">the highest point</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for apex that I've seen before include "Topmost point" , "white collar union" , "Summit or peak" , "Acme" , "Peak, vertex" .)
(Other definitions for tiptop that I've seen before include "The very highest point" , "Quality" , "First-class" , "Best of its kind" , "The height of excellence" .)