Mood disorder (5)
I believe the answer is:
mania
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">mood disorder</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that mania is a type of mood disorder)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for mania that I've seen before include "Mental disorder that results in excessive or violent responses" , "Aberration" , "Craze; overexcitement" , "A (violent) mood disorder" , "wildness" .)