Upside-down cakes cut (4)
I believe the answer is:
snub
'cut' is the definition.
(I know that cut can be written as snub)
'upside-down cakes' is the wordplay.
'upside down' says the letters should be written in reverse.
'cakes' becomes 'buns' (cake is a type of bun).
'buns' written backwards gives 'SNUB'.
(Other definitions for snub that I've seen before include "Spurn; (of nose) turned up at the end" , "'Rebuff, ignore (4)'" , "Give (someone) the cold shoulder" , "Deliberate insult" , "put down" .)