Part of conservation area, an early centre of Christianity (4)
I believe the answer is:
iona
'early centre of christianity' is the definition.
(birthplace of Christianity in Scotland)
'part of conservation area an' is the wordplay.
'part of' indicates the answer is hidden within the clue.
'IONA' is hidden within 'conservation area an'.
(Other definitions for iona that I've seen before include "St Columba's monastery isle" , "Hebridean location" , "Scottish island from where Christianity spread in 563 AD" , "island off Scotland" , "Isolated part of UK" .)