Excellent revolutionary (7)
I believe the answer is:
radical
'revolutionary' is the definition.
(radical can mean revolutionary or extreme)
'excellent' is the wordplay.
I cannot quite understand how this works, but
'excellent' could be 'rad' (slang term) and 'rad' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for radical that I've seen before include "Dial car in order to be drastic" , "Deep-seated" , "Going to the root" , "Going to the roots, fundamental as change may be" , "Subversive" .)