Quiver or quake (7)
I believe the answer is:
tremble
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">quiver</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >'<span class="explanation-format__original">quake</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ ></span>
(Other definitions for tremble that I've seen before include "quail" , "Shake with fear or excitement" , "Shake with fright or cold" , "Shiver slightly as with cold" , "Show fear" .)