Bright, lively (3)
I believe the answer is:
gay
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">bright</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ >'<span class="explanation-format__original">lively</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(similar in meaning)</span><br/ ><br/ ></span>
(Other definitions for gay that I've seen before include "Light-hearted, carefree" , "John --, author of 'The Beggar's Opera'" , "Merry" , "Writer of The Beggar's Opera" , "Homosexual" .)