Everyone in Rome crowds quartet there: men who'd take it all in? (9)

'who'd take it all in?' is the definition.
(omnivores eat meat and vegetables)

'everyone in rome crowds quartet there men' is the wordplay.
I cannot quite understand how this works, but
'quartet' could be 'iv' (Roman numerals for four) and 'iv' is located in the answer.
'men' could be 'or' (Other Ranks: non-commissioned soldiers) and 'or' is found within the answer.
'everyone in rome' could be 'omnes' ('everyone' in Latin) and 'omnes' is found within the leftover letters.
No letters remain.
This may be the basis of the clue (or it may be nonsense).