Anaesthetic enough for three (5)

I believe the answer is:

ether

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'anaesthetic' is the definition.
(ether is a kind of anaesthetic)

'enough for three' is the wordplay.
'three' can be anagrammed to 'ETHER'.
However, I am unsure how this is indicated.

Can you help me to learn more?

(Other definitions for ether that I've seen before include "Colourless liquid used as a solvent" , "Type of chemical" , "Gas - air - space" , "Rare atmosphere" , "Formerly an anaesthetic" .)

I've seen this clue in The Irish Independent.

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