Complaint raised about Democratic Attorney-General’s source of eats (7)

'eats' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.

'complaint raised about democratic attorney-general's source' is the wordplay.
'complaint' becomes 'beef' (beef can mean a complaint or objection).
'raised' says the letters should be written in reverse (going up in a down clue).
'about' means one lot of letters goes inside another.
'democratic' becomes 'd' (political abbreviation).
'source' suggests taking the first letters (source can mean a beginning or origin).
The first letters of 'attorney general' is 'ag'.
'beef' reversed gives 'feeb'.
'feeb' going around 'd' is 'feedb'.
'feedb'+'ag'='FEEDBAG'

'of' is the link.

Can you help me to learn more?