Oily fruit (5)
I believe the answer is:
olive
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">oily fruit</span>' is the definition.<br/ ><span class="explanation-format__explanation">(as in olive oil)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for olive that I've seen before include "Oil producer" , "Small green tree-fruit, nice in martini" , "Yellowy-green colour and fruit" , "It's branch is a symbol of peace" , "Green shade; its branch for peace" .)