Having a coat under the table (9)

I believe the answer is:

plastered

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

I don't understand the rest of the clue.

(Other definitions for plastered that I've seen before include "Smashed" , "Drunk - applied coating to a wall" , "Might ceilings be" , "wasted" , "Drunk (slang)" .)

I've seen this clue in The Guardian.

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