One in the church made to perform duties (8)
I believe the answer is:
minister
'to perform duties' is the definition.
I can't judge whether this defines the answer.
'one in the church' is the wordplay.
'one' becomes 'i' (Roman numeral).
'in the' is an insertion indicator.
'church' becomes 'minster' (minster is a kind of church).
'i' inserted inside 'minster' is 'MINISTER'.
'made' is the link.
Can you help me to learn more?
(Other definitions for minister that I've seen before include "Holder of office in government or church" , "Servant of state or church" , "parliamentarian" , "Parson" , "Merit sin (anag.)" .)