Said to be in favour of youngsters getting nutritious things to eat (8)
I believe the answer is:
proteins
'youngsters getting nutritious things to eat' is the definition.
I can't tell whether this definition defines the answer.
'said to be in favour of' is the wordplay.
I cannot quite understand how this works, but
'in' is present in the answer.
'of' could be 'o' and 'o' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for proteins that I've seen before include "Pointers to organic compounds containing nitrogen, essential in food" , "Long strings of amino acids" , "Organic compounds, obtained from meat, eggs, etc." .)