Piquancy; citrus peel (4)
I believe the answer is:
zest
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">piquancy</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I know that piquancy can be written as zest)</span><br/ ><br/ >'<span class="explanation-format__original">citrus peel</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ ></span>
(Other definitions for zest that I've seen before include "Grated lemon skin" , "Orange-peel" , "Zing" , "Vigour" , "Spirit" .)