Uppermost part (3)
I believe the answer is:
top
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">uppermost part</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 top that I've seen before include "Highest point or position" , "Highest, child's toy" , "Zenith" , "Kill" , "The upper part" .)