Food often used as a measure of comparative frequency (3,7)

'comparative frequency' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.

'food often used as a measure' is the wordplay.
I cannot quite understand how this works, but
'food' could be 'dinner' (dinner is a kind of food) and 'dinner' is located in the answer.
'measure' could be 't' (T is an example) and 't' is found within the answer.
The remaining letters 'hos' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...

'of' is the link.

Can you help me to learn more?