What cannot be contained as filling for bedcovers and pillows? (9)
I believe the answer is:
overspill
If this is the answer I cannot explain how the clue works.
Can you help me to learn more?
(Other definitions for overspill that I've seen before include "for people moving out of slums?" , "Excess; surplus (population)" , "excessive amount" , "Excess liquid" , "Surplus population moving elsewhere" .)