Energy needed for one in humdrum musical setting (2,4)

I believe the answer is:

te deum

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'musical setting' is the definition.
(I know that Te Deum is a hymn tune)

I don't understand the remainder of the clue.

Can you help me to learn more?

(Other definitions for te deum that I've seen before include "Christian hymn of thanksgiving" , "Ancient Christian hymn" , "music" , "Hymn of thanksgiving sung at matins" , "Canticle" .)

I've seen this clue in The Telegraph.

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