Urban sedition somehow becoming defiant (13)
I believe the answer is:
insubordinate
'defiant' is the definition.
(similar in meaning)
'urban sedition somehow' is the wordplay.
'somehow' is an anagram indicator.
'urban'+'sedition'='urbansedition'
'urbansedition' is an anagram of 'INSUBORDINATE'.
'becoming' acts as a link.
(Other definitions for insubordinate that I've seen before include "Defiant of authority" , "Badly behaved" , "undisciplined" , "Recalcitrant" , "Mutinous" .)