Nut used to make marzipan (6)
I believe the answer is:
almond
'nut used to make marzipan' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for almond that I've seen before include "Nut-like kernel" , "Type of nut" , "Nut which provides cake icing" , "Nut (tree)" , "Nutlike seed" .)