In a very cold region with no hint of sun? Yes and no! (7)
I believe the answer is:
iberian
'no' is the definition.
Although both the answer and definition are adjectives, I don't see how they can define each other.
'in a very cold region with no hint of sun? yes' is the wordplay.
I cannot really understand how this works, but
'a' could be 'an' and 'an' is found within the answer.
'region' could be 'e' (E region is an example) and 'e' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'and' is the link.
Can you help me to learn more?
(Other definitions for iberian that I've seen before include "from SW Europe" , "Spaniard, perhaps" , "Person from Spain or Portugal" , "Relating to the area of Spain and Portugal" , "Native of a European peninsula" .)