Make cheerful (7)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">make cheerful</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 hearten that I've seen before include "giving cheer" , "Comfort" , "Make (someone) more confident" , "Make cheerful" , "Be encouraged" .)
(Other definitions for exhilarate that I've seen before include "Thrill" , "Cheer" , "Make very happy or very animated" , "Enliven" .)