Part left over (7)
(Other definitions for remainder that I've seen before include "The part that is left over" , "deposit" , "Dispose of unsold copies of book at a reduced price" , "Leftovers" , "set of unsold books" .)
(Other definitions for remnant that I've seen before include "Leftover piece of cloth" , "Piece or people left over" , "Cloth swatch" , "Little bit left" , "Oddment, leftover piece, perhaps of material" .)