A marine formation north of the Caucasus (8)
I believe the answer is:
armenian
'the caucasus' is the definition.
Although both the answer and definition are singular nouns, I can't understand how one could define the other.
'a marine formation north' is the wordplay.
'formation' indicates anagramming the letters.
'north' becomes 'n' ('N' can be a synonym of 'north').
'marine' is an anagram of 'rmenia'.
'a'+'rmenia'+'n'='ARMENIAN'
'of' is the link.
Can you help me to learn more?
(Other definitions for armenian that I've seen before include "language" , "Eg, native of Yerevan" , "Person from Yerevan, say" , "ethnic group in Asia" , "of the Southern Caucasus" .)