Coastal wind reportedly heading for Alpine mountain region (6)
I believe the answer is:
sierra
'mountain region' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'coastal wind reportedly heading for alpine' is the wordplay.
'coastal' becomes 'si' (I can't explain this - if you can you should give a lot more credence to this answer).
'wind' becomes 'air' (air is a kind of wind).
'reportedly' shows a homophone (sound like).
'heading for' says to take the initial letters.
The initial letter of 'alpine' is 'a'.
'air' sounds like 'err'.
'si'+'err'+'a'='SIERRA'
Can you help me to learn more?
(Other definitions for sierra that I've seen before include "A Spanish chain of mountains" , "Comms code S" , "A range of mountains in Spain" , "Jagged mountains - code word for S" , "One range" .)