Odd patterns seen in part of church (8)
I believe the answer is:
transept
'part of church' is the definition.
(I know that transept is part of church)
'odd patterns' is the wordplay.
'odd' indicates an anagram.
'patterns' is an anagram of 'TRANSEPT'.
'seen in' is the link.
(Other definitions for transept that I've seen before include "Something dividing church in two" , "Wing of cross-shaped church" , "always running north to south" , "Arm of church body" , "Side part of a church" .)