Rod will be faithful (5)

I believe the answer is:

stick

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'rod' is the definition.
(rod is a type of stick)

I don't understand how the rest of the clue works.

(Other definitions for stick that I've seen before include "Adhere - cane" , "Flak - cling" , "Switch < put up" , "Tolerate" , "Glue; piece of wood" .)

I've seen this clue in the Evening Standard.

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