Treacherously bares fencing weapon (5)

I believe the answer is:

sabre

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'weapon' is the definition.
(sabre is a kind of weapon)

'treacherously bares fencing' is the wordplay.
'bares' can be anagrammed to 'SABRE'.
But, I'm unsure how the anagram is indicated.

Can you help me to learn more?

(Other definitions for sabre that I've seen before include "Sword with curved blade" , "Slasher" , "Large wasp" , "Walt --, cartoonist" , "Bares (anag.)" .)

I've seen this clue in The Telegraph.

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