Figure an article to be flexible (5)
I believe the answer is:
lithe
'flexible' is the definition.
(I've seen this before)
'figure an article' is the wordplay.
'figure' becomes 'l' (I've seen this in other clues).
'an' becomes 'i' (Roman numeral for one).
'article' becomes 'the' (the definite article).
'l'+'i'+'the'='LITHE'
'to be' acts as a link.
(Other definitions for lithe that I've seen before include "grace" , "showing great athletic ability" , "Elastic" , "flex with no difficulty" , "able to move supply" .)