Extremely earnest (7)
I believe the answer is:
intense
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">extremely earnest</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for intense that I've seen before include "'Ardent, forceful (7)'" , "Feeling deeply" , "Strong in degree or emotion" , "Deeply felt - extreme" , "Fervent" .)