Flickering patterns seen in part of church (8)
I believe the answer is:
transept
'part of church' is the definition.
('transept' is part of 'church')
'flickering patterns' is the wordplay.
'flickering' is an anagram indicator (I've seen this in other clues).
'patterns' anagrammed gives 'TRANSEPT'.
'seen in' is the link.
(Other definitions for transept that I've seen before include "Part of a church - patterns (anag)" , "Cross-aisle in church" , "Something dividing church in two" , "Patterns in part of church at right angle to nave" , "Part of church intersecting nave" .)