An educational officer on the mountains (6)
I believe the answer is:
andean
'an educational officer on the mountains' is the definition.
I can't judge whether this definition defines the answer.
'an educational officer on' is the wordplay.
'educational officer' becomes 'dean' (I can't justify this - if you can you should give a lot more credence to this answer).
'on' means one lot of letters go next to another.
'an'+'dean'='ANDEAN'
Can you help me to learn more?
(Other definitions for andean that I've seen before include "Relating to South American mountains" , "Like Incas or llamas" , "Of major S. American mountain range" , "Relating to a South American chain" , "within range?" .)