Morag finally consumed gold cake (6)
I believe the answer is:
gateau
'cake' is the definition.
(I know that gateau is a type of cake)
'morag finally consumed gold' is the wordplay.
'finally' says to take the final letters.
'consumed' becomes 'ate' (to eat is to consume food).
'gold' becomes 'Au' (Au is the chemical symbol for gold).
The last letter of 'morag' is 'g'.
'g'+'ate'+'au'='GATEAU'
(Other definitions for gateau that I've seen before include "It's sweet" , "named for Black Forest?" , "Cake (from the Black Forest?)" , "Fancy cake" , "Rich cream cake" .)