Guess this is how nocturnal creatures sleep? (4)

I believe the answer is:

stab

I'm a little stuck... Click here to teach me more about this clue!

'guess' is the definition.
(I've seen this before)

I can't explain the rest of the clue.

(Other definitions for stab that I've seen before include "Puncture" , "Pierce with a dagger" , "Jab" , "Attack with a knife" , "effort" .)

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