Keen enjoyment (4)
I believe the answer is:
zest
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">keen enjoyment</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for zest that I've seen before include "Orange or lemon peel" , "Relish, enthusiasm" , "Grated lemon skin" , "Drive" , "Great energy; citrus peel" .)