Heavy transport group capturing carbon in frozen region (6,6)
I believe the answer is:
arctic circle
'frozen region' is the definition.
The answer and definition can be both locations as well as being singular nouns.
Maybe you can see an association between them that I don't see?
'heavy transport group capturing carbon' is the wordplay.
'heavy transport' becomes 'artic' (I am not sure about this - if you are sure you should believe this answer much more).
'group' becomes 'circle' (I've seen this in other clues).
'capturing' indicates putting letters inside.
'carbon' becomes 'C' (chemical symbol).
'artic'+'circle'='articcircle'
'articcircle' enclosing 'c' is 'ARCTIC CIRCLE'.
'in' is the link.
Can you help me to learn more?
(Other definitions for arctic circle that I've seen before include "Imaginary line at approximately latitude 66 degrees 32' North" , "Top of the world" , "Line circling the north pole" , "In parallel" .)