Operated on ram with anaesthetic (6)

I believe the answer is:

wether

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

'operated on ram with anaesthetic' is the definition.
I can't judge whether this definition defines the answer.

'with anaesthetic' is the wordplay.
'with' becomes 'w' (abbreviation).
'anaesthetic' becomes 'ether' (ether is a kind of anaesthetic).
'w'+'ether'='WETHER'

Can you help me to learn more?

(Other definitions for wether that I've seen before include "Male sheep" , "Castrated 22dn" , "Castrated ram" , "Castrated sheep" .)

I've seen this clue in The Sunday Times.

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