Some yobbos looted European capital (4)
I believe the answer is:
oslo
'european capital' is the definition.
(I've seen this before)
'some yobbos looted' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'OSLO' is hidden in the letters of 'yobbos looted'.
(Other definitions for oslo that I've seen before include "Nordic capital" , "Solo in Norway?" , "Northern capital of Czechoslovakia?" , "Norway's capital city" , "European capital in go-slow" .)