Remaining, leftover (8)
I believe the answer is:
residual
<span class="explanation-format__ClueExplanation">I believe this is a double definition.<br/ ><br/ >'<span class="explanation-format__original">remaining</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I know that remaining can be written as residual)</span><br/ ><br/ >'<span class="explanation-format__original">leftover</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 residual that I've seen before include "Leftover - used rail (anag)" , "unused" , "Remaining at the end" , "Concerning what is left over" , "Pertaining to what is left over" .)