Society in same old routine to deteriorate (4)

I believe the answer is:

rust

(Other definitions for rust that I've seen before include "Reddish coating formed on iron through 11 across" , "Reddish-brown coating formed on metal by moisture" , "A fungus; a corrosion" , "Reddish-brown oxide coating" , "Reddish oxide coating on iron" .)

I've seen this clue in The Sun.

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