Broken patterns in cathedral wing (8)
I believe the answer is:
transept
'cathedral wing' is the definition.
(part of a cathedral)
'broken patterns' is the wordplay.
'broken' is an anagram indicator.
'patterns' anagrammed gives 'TRANSEPT'.
'in' acts as a link.
(Other definitions for transept that I've seen before include "It crosses the nave in church" , "Part of church off aisle" , "Part of a church - patterns (anag)" , "Wing of cross-shaped church" , "Arm of church body" .)