Bares disguised weapon (5)
I believe the answer is:
'weapon' is the definition.
(I know that sabre is a type of sword)
'bares disguised' is the wordplay.
'disguised' is an anagram indicator.
'bares' with letters rearranged gives 'SABRE'.
(Other definitions for sabre that I've seen before include "Heavy cavalry sword" , "Bares (anag.)" , "weapon" , "Sword (that may be rattled)" , "Walt --, cartoonist" .)