Nothing but a metal product, yet of vegetable origin (7)
I believe the answer is:
oatmeal
'of vegetable origin' is the definition.
The definition suggests a singular noun which matches the answer.
'nothing but a metal product' is the wordplay.
I cannot quite understand how this works, but
'nothing' could be 'o' (O resembles 0) and 'o' is found in the answer.
'a' is present in the answer.
an anagram of 'metal' is 'tmeal' which is located in the answer.
This accounts for all the letters.
This explanation may well be incorrect...
'yet' is the link.
Can you help me to learn more?
(Other definitions for oatmeal that I've seen before include "greyish-yellow colour" , "Sort of beige" , "AA Motel (anag.)" , "Ground grain used to make porridge" , "Ground grain; colour" .)