Promise to take edge off blade (4)

I believe the answer is:

word

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'promise' is the definition.
(as in 'I give you my word')

I can't explain the remainder of the clue.

(Other definitions for word that I've seen before include "See 21" , "The Bible is the . . . . of God" , "Term" , "News; speech element" , "Promise; news" .)

I've seen this clue in The Independent.

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