Grace warbles singing from the heart (8)

I believe the answer is:

blessing

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But I can't explain it at all! Could you help me understand?

(Other definitions for blessing that I've seen before include "Grace said before a meal" , "Protecting prayer" , "Approval" , "Beneficial thing for which one is grateful" , "Glibness in benediction" .)

I've seen this clue in The Sun.

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