I am able to follow barrel to religious centre (7)
I believe the answer is:
vatican
'religious centre' is the definition.
(centre of Catholicism)
'i am able to follow barrel' is the wordplay.
'i am able' becomes 'I can' (I can).
'to follow' is a charade indicator (letters next to each other) (some letters go after or follow others).
'barrel' becomes 'vat' (a vat is a large tub or barrel).
'ican' put after 'vat' is 'VATICAN'.
'to' is the link.
(Other definitions for vatican that I've seen before include "Holy See" , "Papacy" , "ecclesiastical centre" , "City within Rome" , "Pope's home" .)