Greeting seen when Rachel and Louise meet (5)

I believe the answer is:

hello

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'greeting' is the definition.
(hello is a kind of greeting)

I don't understand the rest of the clue.

(Other definitions for hello that I've seen before include "opener?" , "Look at that" , "Introductory greeting" , "Musical with Satchmo and Streisand" , "Greeting - celebrity magazine" .)

I've seen this clue in The Independent.

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