Drink a pious person under the table! (5)

I believe the answer is:

stout

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

'drink' is the definition.
(stout is a kind of drink)

'a pious person under the table' is the wordplay.
'a pious person' becomes 'st' (saint).
'under the table' becomes 'out' (I can't justify this - if you can you should believe this answer much more).
'st'+'out'='STOUT'

Can you help me to learn more?

(Other definitions for stout that I've seen before include "Bulky" , "Portly or stalwart" , "Dark beer for the rather fat" , "Rather fat, stocky" , "pint" .)

I've seen this clue in the Evening Standard.

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