Brazilian port or I am wrong (3)

I believe the answer is:

rio

I'm a little stuck... Click here to teach me more about this clue!

'brazilian port' is the definition.
(I've seen this in another clue)

'or i am wrong' is the wordplay.
'or i' anagrams to 'RIO'.
But, I'm not sure how the anagram is indicated.

Can you help me to learn more?

(Other definitions for rio that I've seen before include "Port, -- de Janeiro" , "Location of next Olympic Games, in short" , "A Mexican river - like Grande" , "The ... Grande borders Texas and Mexico" , "(Golfer) in the sand" .)

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

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