Abdominal organ — bad temper (6)
I believe the answer is:
spleen
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">abdominal organ</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >'<span class="explanation-format__original">bad temper</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(informal term for bad temper)</span><br/ ><br/ ></span>
(Other definitions for spleen that I've seen before include "Internal organ - irascibility" , "Organ of the body - ill temper" , "Body organ; spite" , "Organ causing bad temper?" , "Acrimony" .)