Baking staple (5)
I believe the answer is:
sugar
'baking staple' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sugar that I've seen before include "--- Ray Robinson, boxer" , "Cane or beet product" , "Sweetening agent" , "e.g. Glucose" , "Plantation product" .)