Tense and easily upset (6,6)
I believe the answer is:
highly strung
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">tense and easily upset</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for highly strung that I've seen before include "Excitable - easily upset" , "Very sensitive" , "Very nervous or volatile" , "Tense and easily upset" , "Nervous, easily upset" .)