Ban a revolutionary fellow in Bahrain, maybe (4)
I believe the answer is:
arab
'fellow in bahrain maybe' is the definition.
(Bahrain is an Arab country)
'ban a revolutionary' is the wordplay.
'ban' becomes 'bar' (I've seen this before).
'revolutionary' is a reversal indicator.
'bar'+'a'='bara'
'bara' back-to-front is 'ARAB'.
(Other definitions for arab that I've seen before include "Saudi or Omani, perhaps" , "Small riding horse" , "One from the Middle East or North Africa" , "Saudi, e.g." , "Person from the Middle East, say" .)