Pouring oil on troubled waters is the job of 14 across

I believe the answer is:

peace-keeping

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'across' is the definition.
Both the answer and definition are adjectives.
Maybe you can see an association between them that I don't see?

I can't explain the rest of the clue.

Can you help me to learn more?

(Other definitions for peace-keeping that I've seen before include "The Blue Berets' remit" , "United Nations speciality" , "UN speciality" .)

I've seen this clue in the Irish Times.

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