Stupid person, American, becomes an emperor (5)

I believe the answer is:

titus

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'an emperor' is the definition.
(Roman emperor)

'stupid person american' is the wordplay.
'stupid person' becomes 'tit' (I can't explain this - if you can you should give a lot more credence to this answer).
'american' becomes 'US' (abbreviation for United States).
'tit'+'us'='TITUS'

'becomes' is the link.

Can you help me to learn more?

(Other definitions for titus that I've seen before include "Rom. emperor 79 to 81AD" , "saint" , "Roman emperor, son of Vespasian" , "Only part of Shakespeare play" , "Roman emperor from AD79" .)

I've seen this clue in The Guardian.

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