Liquid remnants (5)
(Other definitions for dregs that I've seen before include "Residue of drink" , "Sediment, lees" , "Wine sediment" , "Leftover drink, sediment" , "Sediment, grounds" .)
(Other definitions for residue that I've seen before include "Material left" , "Remains to be seen" , "What remains of something" , "Stuff left over" , "Surplus" .)