Peninsula in Russian region son leaves (6)
I believe the answer is:
iberia
'peninsula' is the definition.
(Iberia is an example)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for iberia that I've seen before include "European countries" , "Spain's national flag-carrying airline" , "Spain and Portugal - airline" , "Peninsula encompasing Spain and Protugal" , "Spain and Portugal (6)" .)