Personality disorder (8)
I believe the answer is:
neurosis
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">personality disorder</span>' is the definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for neurosis that I've seen before include "Mild mental condition" , "Trouble in mind" , "Mild condition such as obsessive behaviour" , "Resinous (anag) -- unspecific personality disturbance" , "So insure against the nervous disorder" .)