Stir violently; perturb (7)
I believe the answer is:
agitate
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">stir violently</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">perturb</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ ></span>
(Other definitions for agitate that I've seen before include "Disturb or shake" , "Trouble, make nervous" , "Stir vigorously" , "Make troubled or nervous" , "Disturb, cause to worry" .)