One dining after church can't be trusted (5)

I believe the answer is:

eater

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'one dining' is the definition.
(someone eating a meal)

I cannot understand how the rest of the clue works.

(Other definitions for eater that I've seen before include "type of fruit" , "Apple, perhaps" , "Fruit (but not a cooker)" , "Person taking course" , "Type of apple" .)

I've seen this clue in The Irish Times.

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