Zulu on barge moved around city (6)
I believe the answer is:
zagreb
'city' is the definition.
(largest city in Croatia)
'zulu on barge moved' is the wordplay.
'zulu' becomes 'z' (phonetic alphabet: alpha, bravo, charlie etc.**).
'on' is an insertion indicator.
'moved' indicates anagramming the letters.
'barge' with letters rearranged gives 'agreb'.
'z' put within 'agreb' is 'ZAGREB'.
'around' acts as a link.
(Other definitions for zagreb that I've seen before include "Capital city of Croatia" , "Croatia's capital city" , "Croatian city" , "European city" , "European capital" .)