A leading article I see as out-of-date (7)
I believe the answer is:
archaic
'out-of-date' is the definition.
(thesaurus)
'a leading article i see' is the wordplay.
'a leading' becomes 'arch' (e.g. in arch-enemy).
'article' becomes 'a' (the indefinite article in English).
'see' becomes 'C' (the word for the letter, according to Chambers).
'arch'+'a'+'i'+'c'='ARCHAIC'
'as' acts as a link.
(Other definitions for archaic that I've seen before include "Behind the times" , "Obsolete" , "From the past" , "Extremely old" , "Ancient or out of date" .)