Core, heart (6)
(Other definitions for centre that I've seen before include "'Things fall apart; the ... cannot hold'/Yeats" , "See 24" , "See 1" , "Point equidistant from all other points" , "Recent (anag)" .)
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">core</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >'<span class="explanation-format__original">heart</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know that heart can be written as middle)</span><br/ ><br/ ></span>
(Other definitions for middle that I've seen before include "One of 21 [HEARTS]" , "Equally distant from the extremes" , "Group of clubs; distance" , "Median" , "It's equidistant from the extremes" .)