Perched upon (4)
I believe the answer is:
atop
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">perched upon</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 atop that I've seen before include "At the apex" , "On the peak" , "On the highest point" , "Surmounting" , "Positioned on" .)