Grin, beam (5)
I believe the answer is:
smile
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">grin</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >'<span class="explanation-format__original">beam</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that beam is a more specific form of smile)</span><br/ ><br/ ></span>
(Other definitions for smile that I've seen before include "Pleased expression" , "Indicate pleasure with lips movement" , "Look happy" , "Show happiness" , "Show amusement or pleasure" .)