Notice Yankee attack butter (5,4)

I believe the answer is:

billy goat

'butter' is the definition.
(animal which butts)

'notice yankee attack' is the wordplay.
'notice' becomes 'bill' (both can mean an advertisement).
'yankee' becomes 'Y' (phonetic alphabet: alpha, bravo, charlie etc.).
'attack' becomes 'goat' (go at).
'bill'+'y'+'goat'='BILLY-GOAT'

I've seen this clue in The Times.

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