An opening word from Ali Baba (6)

I believe the answer is:

sesame

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'an opening word' is the definition.
(I've seen this in another clue)

I don't understand the rest of the clue.

(Other definitions for sesame that I've seen before include "Part of code for opening" , "Ali Baba's opening command" , "Open . . . . . . is a magic phrase to gain entry" , "Plant with oily seeds" , "which magically opens" .)

I've seen this clue in the Evening Standard.

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