Extreme edge (5)
I believe the answer is:
brink
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">extreme edge</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for brink that I've seen before include "Edge of precipice" , "Verge (of war etc)" , "Edge (of disaster etc)" , "Threshold" , "Verge of an event" .)