Rebel, Republican in transition (13)

I believe the answer is:

revolutionary

'rebel' is the definition.
(thesaurus)

'republican in transition' is the wordplay.
'republican' becomes 'r' (abbreviation).
'in transition' becomes 'evolutionary'.
'r'+'evolutionary'='REVOLUTIONARY'

(Other definitions for revolutionary that I've seen before include "New" , "Insurgent - involving dramatic change" , "agitator" , "Innovative" , "French calendar?" .)

I've seen this clue in The Telegraph.

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