Of whom it might be said: 'You are what you eat' (8)
I believe the answer is:
cannibal
'of' is the definition.
Both the definition and answer are singular nouns.
Perhaps you can see an association between them that I don't see?
'it might be said you are what you eat' is the wordplay.
I cannot really understand how this works, but
'might' could be 'can' and 'can' is present in the answer.
'are' could be 'a' (short for 'are', historical unit of measurement) and 'a' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
'whom' is the link.
Can you help me to learn more?
(Other definitions for cannibal that I've seen before include "One eats human flesh" , "One who eats its own species" , "Animal that eats its own kind" , "Eater of one's own kind" , "Anthropophagite" .)