Make better or more attractive (7)
I believe the answer is:
enhance
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">make better or more attractive</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for enhance that I've seen before include "'Improve, augment (7)'" , "Improve, add to attractiveness of" , "Raise in value or quality" , "Improve the value of (something)" , "Increase in power" .)