Ivan flew after article like a bird (5)
I believe the answer is:
avian
'like a bird' is the definition.
(I've seen this in another clue)
'ivan flew after article' is the wordplay.
'flew' indicates anagramming the letters (I've seen 'fly' mean this).
'after' is a charade indicator (letters next to each other).
'article' becomes 'a' (the indefinite article in English).
'ivan' with letters rearranged gives 'vian'.
'vian' put after 'a' is 'AVIAN'.
(Other definitions for avian that I've seen before include "Lizard with adhesive foot-pads" , "Relating to birds" , "Birdlike" , "Pertaining to or characteristic of birds" , "Like rails, for example" .)