Comments in the book on chiropody? (9)

'comments' is the definition.
(footnote is a kind of comment)

'the book on chiropody?' is the wordplay.
I cannot quite see how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found within the answer.
'book' could be 'ot' (I've seen this in other clues) and 'ot' is located in the answer.
'on' could be 'o' (I've seen this in other clues) and 'o' is present in the answer.
This may be the basis of clue (or it may be nonsense).

'in' is the link.

Can you help me to learn more?