Could be roaming with us, but one doesn’t know (9)

I believe the answer is:

ignoramus

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'one doesn't know' is the definition.
I can't tell whether this defines the answer.

'could be roaming with us' is the wordplay.
'could be' indicates anagramming the letters.
'with' is a charade indicator (letters next to each other).
'roaming' is an anagram of 'ignoram'.
'ignoram'+'us'='IGNORAMUS'

'but' is the link.

Can you help me to learn more?

(Other definitions for ignoramus that I've seen before include "I wouldn't know" , "Simpleton" , "One lacking knowledge" , "A know-nothing" , "One is not intelligent" .)

I've seen this clue in The Hindu.

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