Apple refuse (4)
I believe the answer is:
core
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">apple refuse</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 core that I've seen before include "Crux" , "The centre of an object" , "Drilled rock sample" , "Nucleus" , "Heart of the matter" .)