Clergyman made a confession to some extent (6)
I believe the answer is:
deacon
'clergyman' is the definition.
(I know that deacon is a type of clergyman)
'made a confession to some extent' is the wordplay.
'to some extent' says the answer is hidden in the clue.
'DEACON' can be found hidden inside 'made a confession'.
(Other definitions for deacon that I've seen before include "Layman attending to church duties" , "A member of the lower orders of clergy" , "Churchman" , "Church post" , "Church minister" .)