Worry, unnerve (7)
I believe the answer is:
perturb
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">worry</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(to perturb is to worry or unsettle someone)</span><br/ ><br/ >'<span class="explanation-format__original">unnerve</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ ></span>
(Other definitions for perturb that I've seen before include "Make unsettled" , "Disturb greatly" , "Unsettle, make anxious" , "Opera star" , "Worry" .)