Thoughtful way the American goes round a Brazilian city (7)
I believe the answer is:
serious
'thoughtful' is the definition.
(similar in meaning)
'way the american goes round a brazilian city' is the wordplay.
'way' becomes 'se' (I am not sure about this - if you are sure you should believe this answer much more).
'the american' becomes 'us' (abbreviation for United States).
'goes round' is an insertion indicator.
'a brazilian city' becomes 'rio' (Rio de Janeiro).
'se'+'us'='seus'
'seus' going around 'rio' is 'SERIOUS'.
Can you help me to learn more?
(Other definitions for serious that I've seen before include "Earnest; vital" , "Stern" , "Not light or frivolous" , "Solemn, thoughtful" , "Important - solemn" .)