Clergyman keeping company with another (6)
I believe the answer is:
deacon
'clergyman' is the definition.
(I know that deacon is a type of clergyman)
'keeping company with another' is the wordplay.
'keeping' is an insertion indicator.
'company' becomes 'co' (abbreviation).
'with another' becomes 'dean' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'co' placed inside 'dean' is 'DEACON'.
(Other definitions for deacon that I've seen before include "Cleric ranking just below a priest in Christian churches" , "Layman attending to church duties" , "An ordained minister" , "A member of the lower orders of clergy" , "Churchman" .)