Rome collapsed in excess, may I add (8)

I believe the answer is:

moreover

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'i add' is the definition.
I can't judge whether this defines the answer.

'rome collapsed in excess' is the wordplay.
'collapsed' indicates anagramming the letters.
'in excess' becomes 'over' (I've seen this in other clues).
'rome' anagrammed gives 'more'.
'more'+'over'='MOREOVER'

'may' is the link.

Can you help me to learn more?

(Other definitions for moreover that I've seen before include "Furthermore, in addition" , "Besides, in addition" , "as well" .)

I've seen this clue in The Guardian and The Globe and Mail.

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