Upper class in tiaras travelling in Europe (7)
I believe the answer is:
austria
'in europe' is the definition.
('Austria' is part of 'europe')
'upper class in tiaras travelling' is the wordplay.
'upper class' becomes 'u'.
'in' means one lot of letters goes inside another.
'travelling' indicates anagramming the letters.
'tiaras' anagrammed gives 'astria'.
'u' placed inside 'astria' is 'AUSTRIA'.
(Other definitions for austria that I've seen before include "Its ruling house was the Hapsburgs" , "The capital is Vienna (7)" , "One state" , "Landlocked European country" , "Country of Graz and Linz" .)