Scornfully reject cakes that are sent back (4)
I believe the answer is:
snub
'scornfully reject' is the definition.
'snub' can be an answer for 'reject' (snubbing is a kind of rejecting). I am not certain of the 'scornfully' bit.
'cakes that are sent back' is the wordplay.
'cakes' becomes 'buns' (cake is a type of bun).
'that are sent back' is a reversal indicator.
'buns' backwards is 'SNUB'.
Can you help me to learn more?
(Other definitions for snub that I've seen before include "Rebuff; brush-off" , "Shun" , "Rebuff with buns" , "Refuse to acknowledge" , "put down" .)