It's uncommon for society to worry about carbon (6)
I believe the answer is:
scarce
'it's uncommon' is the definition.
(I've seen this before)
'society to worry about carbon' is the wordplay.
'society' becomes 's' (common abbreviation in names of organisations).
'to worry' becomes 'care' (I've seen this before).
'about' indicates putting letters inside.
'carbon' becomes 'c' (C is the chemical symbol for carbon).
'care' placed around 'c' is 'carce'.
's'+'carce'='SCARCE'
'for' acts as a link.
(Other definitions for scarce that I've seen before include "Common? Definitely not" , "Few and far between" , "Rarely found" , "Deficient in quantity" , "Hard to get" .)