Reach the highest point (4)
I believe the answer is:
peak
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">reach the highest point</span>' is the definition.<br/ ><span class="explanation-format__explanation">(peak can mean to reach a maximum point)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for peak that I've seen before include "Reach the highest point" , "Part of cap; mountain" , "Mountain top" , "maximum pitch" , "Acme" .)