One who stayed in bed (5)

I believe the answer is:

layer

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'bed' is the definition.
(I know that bed can be written as layer)

I don't understand the remainder of the clue.

(Other definitions for layer that I've seen before include "Hen, perhaps" , "Productive chicken" , "Thin sheet - productive hen" , "Single thickness, tier" , "Stratum; chicken" .)

I've seen this clue in The Globe and Mail.

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