Beer for mates? That's stout! (5)

I believe the answer is:

round

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'that's stout' is the definition.
(I've seen this before)

I can't explain the rest of the clue.

(Other definitions for round that I've seen before include "Circular - 18 holes" , "stout" , "Drinks order" , "Shaped like a circle" , "rung of the ladder" .)

I've seen this clue in The Sun.

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