Short religious book found in diocese, written round about 250 (6)

I believe the answer is:

eccles

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'short religious book' is the definition.
(abbreviation for Ecclesiastes)

I cannot understand how the remainder of the clue works.

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(Other definitions for eccles that I've seen before include "Lancashire town" , "Town known for cakes" , "Town in Greater Manchester, selling its own cakes since 1793" , "Kind of cake - abbreviation for book in Bible" , "spotted cake" .)

I've seen this clue in The Independent.

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