Unable to settle (8)
I believe the answer is:
restless
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">unable to settle</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for restless that I've seen before include "Unable to sit still" , "Ill at ease" , "Uneasy and agitated" , "Unable to settle" , "Fidgetty" .)