Genuine article about limiting carbon (4)
I believe the answer is:
echt
'genuine' is the definition.
(echt means genuine or authentic)
'article about limiting carbon' is the wordplay.
'article' becomes 'the' (the definite article in English).
'about' is a reversal indicator.
'limiting' is an insertion indicator.
'carbon' becomes 'C' (chemical symbol).
'the' reversed gives 'eht'.
'eht' placed around 'c' is 'ECHT'.
(Other definitions for echt that I've seen before include "Genuine (German)" , "Genuine - authentic" , "Really" , "German's real" , "Genuine -- honest" .)