Most balanced article on Sweden is in French (6)
I believe the answer is:
sanest
'most balanced' is the definition.
'article on sweden is in french' is the wordplay.
'article' becomes 'an' (indefinite article).
'on' means one lot of letters go next to another.
'sweden' becomes 's'.
'is in french' becomes 'est' (I've seen this in other clues).
'an' put after 's' is 'san'.
'san'+'est'='SANEST'
(Other definitions for sanest that I've seen before include "Mentally most healthy" , "Most rational and logical" , "Most sensible" , "Most rational and reasonable" , "Assent, being most rational" .)