Article seen by chief is to come (5)
I believe the answer is:
ahead
'is to come' is the definition.
(ahead means still to come)
'article seen by chief' is the wordplay.
'article' becomes 'a' (the indefinite article in English).
'seen by' is a charade indicator (letters next to each other).
'chief' becomes 'head' (synonyms).
'a'+'head'='AHEAD'
(Other definitions for ahead that I've seen before include "advanced" , "Forwards" , "In the vanguard" , "In front as in race" , "Forward - in front" .)