One in part of the church devoid of sophistication (5)
I believe the answer is:
naive
'one in part of the church devoid of sophistication' is the definition.
I can't tell whether this definition defines the answer.
'one in part of the church' is the wordplay.
'one' becomes 'i' (Roman numeral).
'in' means one lot of letters goes inside another.
'part of the church' becomes 'nave' ('nave' is part of 'church').
'i' inserted within 'nave' is 'NAIVE'.
Can you help me to learn more?
(Other definitions for naive that I've seen before include "Lacking sophistication" , "Too innocent or gullible" , "Ingenuous and credulous" , "Credulous, unworldly" , "Callow" .)