Lose Pat, revolutionary supporter (7)
I believe the answer is:
apostle
'supporter' is the definition.
(apostle is a kind of supporter)
'lose pat revolutionary' is the wordplay.
'revolutionary' is an anagram indicator.
'lose'+'pat'='losepat'
'losepat' anagrammed gives 'APOSTLE'.
(Other definitions for apostle that I've seen before include "Chosen disciple" , "Early Christian missionary" , "Ale pots (anag)" , "Champion - one of twelve" , "James, perhaps" .)