Tether an excitable cow (8)

I believe the answer is:

threaten

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'cow' is the definition.
(I've seen this before)

'tether an excitable' is the wordplay.
'tether an' anagrams to 'THREATEN'.
Though, I'm not sure how the anagram is indicated.

Can you help me to learn more?

(Other definitions for threaten that I've seen before include "indicate danger" , "Warn of violence" , "Be menacing" , "Menace - impend" , "Utter intentions of injury or punishment" .)

I've seen this clue in The Sun.

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