What's Brains in Wales? (3)

I believe the answer is:

ale

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

'what's brains' is the definition.
I can't tell whether this defines the answer.

'in wales?' is the wordplay.
'in' indicates the answer is hidden within the clue.
'ALE' can be found hidden inside 'wales'.

Can you help me to learn more?

(Other definitions for ale that I've seen before include "English beer, mild or bitter" , "Sold in 23" , "Booze" , "Alcohol" , "Beer consumed in sales" .)

I've seen this clue in The Sun.

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