Quick temper (5,4)
I believe the answer is:
short fuse
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">quick temper</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 short fuse that I've seen before include "irascibility" , "Quick temper (little piece of wire?)" , "On which one is quick to lose one's temper" .)