Believed to have quoted a revolutionary in (8)
I believe the answer is:
credited
'believed' is the definition.
(thesaurus)
'quoted a revolutionary in' is the wordplay.
'quoted' becomes 'cited' ('cite' can be a synonym of 'quote').
'a revolutionary' becomes 'red'.
'in' means one lot of letters goes inside another.
'cited' placed around 'red' is 'CREDITED'.
'to have' is the link.
(Other definitions for credited that I've seen before include "Acknowledged as writer" , "given improved balance" , "Believed" , "Esteemed" , "3 across (anag.)" .)