Some other article (3)
I believe the answer is:
the
'article' is the definition.
(the 'definite article' part of speech)
'some other' is the wordplay.
'some' indicates the answer is hidden within the clue (some of the parts of the word are used).
'THE' can be found hidden inside 'other'.
(Other definitions for the that I've seen before include "Finis" , "15, 16 One given taste of own medicine" , "Over - - moon" , "Article is quite definite" , "The most frequently occurring word in the Bible (and in this clue!)" .)