Greeting old country, it's to do with mountains (8)
I believe the answer is:
himalaya
'to do with mountains' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.
'greeting old country' is the wordplay.
'greeting' becomes 'hi' (hi is a kind of greeting).
'old country' becomes 'malaya' (Malaya is an example. I am not sure about the 'old' bit.).
'hi'+'malaya'='HIMALAYA'
'it's' acts as a link.
Can you help me to learn more?
(Other definitions for himalaya that I've seen before include "massive range" , "World's highest mountain range" .)