School, extremely fine, raised comment (8)
I believe the answer is:
footnote
'school extremely fine raised comment' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'school extremely fine raised comment' is the wordplay.
'school extremely' becomes 'too' (I can't explain this - if you can you should give a lot more credence to this answer).
'fine' becomes 'f' (abbreviation).
'raised' says the letters should be written in reverse.
'comment' becomes 'note' (note is a kind of comment).
'too'+'f'='toof'
'toof' reversed gives 'foot'.
'foot'+'note'='FOOTNOTE'
Can you help me to learn more?
(Other definitions for footnote that I've seen before include "addition to manuscript" , "Text at page end" , "Too often at bottom of page" , "Minor reference" , "Text explanation" .)