Pulsating (7)
(Other definitions for vibrant that I've seen before include "Vivacious" , "Bright, thrilling or resonant" , "Lively; pulsating" , "Dynamic" , "Aquiver with life and excitement" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">pulsating</span>' is the definition.<br/ ><span class="explanation-format__explanation">('throb' can be a synonym of 'pulsate')</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for throbbing that I've seen before include "Beating" , "Pulsating" .)