Various patterns in area crossing nave (8)
I believe the answer is:
transept
'area crossing nave' is the definition.
(part of church)
'various patterns' is the wordplay.
'various' indicates anagramming the letters.
'patterns' anagrammed gives 'TRANSEPT'.
'in' acts as a link.
(Other definitions for transept that I've seen before include "Patterns found in parts of church" , "Cross-aisle in church" , "Part of church intersecting nave" , "Something dividing church in two" , "always running north to south" .)