Pulsate or pound (5)
I believe the answer is:
throb
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">pulsate</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >'<span class="explanation-format__original">pound</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ ></span>
(Other definitions for throb that I've seen before include "Strong regular beat" , "Pulsate strongly" , "Have strong or irregular heartbeat" , "Beat strongly" , "Drum" .)