Unused, leftover (5)
I believe the answer is:
spare
I believe this is a double definition.
'unused' is the first definition.
(thesaurus)
'leftover' is the second definition.
(I've seen this before)
(Other definitions for spare that I've seen before include "Pardon; unneeded" , "Leftover" , "show mercy" , "Excess to requirements" , "With no excess fat" .)