Environment is declining (7)

I believe the answer is:

setting

This clue is a double definition.

'environment' is the first definition.
(I know that environment can be written as setting)

'is declining' is the second definition.
(thesaurus)

(Other definitions for setting that I've seen before include "Environment" , "approaching the horizon" , "Where one may find Ruby" , "Dropping beneath the horizon" , "Mount for gem" .)

I've seen this clue in The Sun.

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