Familiar form of grub chewed by diners without much noise (7)

'diners without much noise' is the definition.
I don't know anything about this answer so I can't judge whether it can be defined by this definition.

'familiar form of grub chewed by' is the wordplay.
'familiar form of' becomes 'ers' (I can't explain this - if you can you should give a lot more credence to this answer).
'chewed' is an anagram indicator.
'by' is a charade indicator (letters next to each other).
'grub' anagrammed gives 'burg'.
'ers' after 'burg' is 'BURGERS'.

Can you help me to learn more?