Food in the top layer, it’s off and extremely raw (7)
I believe the answer is:
crudest
'extremely raw' is the definition.
(I've seen this before)
'food in the top layer it's off' is the wordplay.
'food in the top layer' becomes 'crude' (I can't justify this - if you can you should give a lot more credence to this answer).
'off' is an anagram indicator.
'ts' anagrammed gives 'st'.
'crude'+'st'='CRUDEST'
'and' is the link.
Can you help me to learn more?
(Other definitions for crudest that I've seen before include "Most vulgar" , "extremely raw" , "Most basic" .)