Even-tempered (6)
I believe the answer is:
placid
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">even-tempered</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that even-tempered can be written as placid)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for placid that I've seen before include "Peaceable and not easily disturbed" , "Quiet and still" , "Calm and not easily upset" , "Calm, peaceful" , "without ruffles" .)