Bombastic, defiant revolutionary crosses line (8)
I believe the answer is:
inflated
'bombastic' is the definition.
(I've seen this before)
'defiant revolutionary crosses line' is the wordplay.
'revolutionary' indicates an anagram.
'crosses' is an insertion indicator.
'line' becomes 'l'.
'defiant' anagrammed gives 'infated'.
'infated' placed around 'l' is 'INFLATED'.
(Other definitions for inflated that I've seen before include "Bombastic" , "Flan diet (anag.)" , "Extravagant" , "Exaggerated (and liable to 5?)" , "Filled with air or gas to distend" .)