Agree end will be terrible for traitor (8)

I believe the answer is:

renegade

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'for traitor' is the definition.
(I've seen this in another clue)

'agree end will be terrible' is the wordplay.
'agree end' anagrams to 'RENEGADE'.
However, I'm not sure how this is indicated.

Can you help me to learn more?

(Other definitions for renegade that I've seen before include "Traitor" , "disloyal type" , "Treacherous deserter" , "Deserter, turncoat" , "A deserter from a cause or faith" .)

I've seen this clue in The Guardian and The Sun.

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