Rowdy trio travelling round America (7)
I believe the answer is:
riotous
'rowdy' is the definition.
(I've seen this before)
'trio travelling round america' is the wordplay.
'travelling' indicates anagramming the letters.
'round' becomes 'o' (o is a circular letter).
'america' becomes 'US' (United States).
'trio' anagrammed gives 'riot'.
'riot'+'o'+'us'='RIOTOUS'
(Other definitions for riotous that I've seen before include "Unruly U rebellious" , "Wild, disorderly" , "Anarchic" , "Behaving wildly" , "wild and unruly" .)