Northern river retains atmosphere and character (6)
I believe the answer is:
nature
'character' is the definition.
(I know that character can be written as nature)
'northern river retains atmosphere' is the wordplay.
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'river' becomes 'ure' (river in Yorkshire).
'retains' is an insertion indicator.
'atmosphere' becomes 'at' (abbreviation).
'n'+'ure'='nure'
'nure' enclosing 'at' is 'NATURE'.
'and' acts as a link.
(Other definitions for nature that I've seen before include "Fundamental character" , "what's seen in the country?" , "The world with all its features found in tea-urn" , "Tea-urn for outdoors" , "Essential character" .)