Marzipan ingredient (6)
I believe the answer is:
almond
'marzipan ingredient' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for almond that I've seen before include "Yellowish brown" , "Fruit kernel of a peach-related tree" , "Fruit for marzipan" , "Nut often used in cake icing (6)." , "Nut-like kernel" .)