In the Bible, a protector (3)

I believe the answer is:

bib

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'in' is the definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.

I don't understand the rest of the clue.

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(Other definitions for bib that I've seen before include "Protective apron" , "Protective cloth; fish" , "Protective clothing - fish" , "Protective garment" , "Fish; athlete's vest" .)

I've seen this clue in the Evening Standard.

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