Plain egg flipped, while drinking cordial? (6)

I believe the answer is:

genial

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

'cordial?' is the definition.
(I know that cordial can be written as genial)

'plain egg flipped while drinking' is the wordplay.
'GENIAL' is hidden back-to-front within the letters.
But, I'm not sure how the hidden word is indicated.

Can you help me to learn more?

(Other definitions for genial that I've seen before include "'Cheerful, friendly, sociable (6)'" , "Jolly" , "Cordial" , "Agreeable in Ealing" , "Cheerful and well-disposed" .)

I've seen this clue in The Irish Times.

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