Nervous, tense (2,4)
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">nervous</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(on edge can mean nervous or tense)</span><br/ ><br/ >'<span class="explanation-format__original">tense</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(on edge can mean tense or stressed)</span><br/ ><br/ ></span>
(Other definitions for on edge that I've seen before include "Tense and irritable, with nerves stretched" , "Apprehensive" , "close to border" , "stressed" , "Twitchy" .)