Many an article is supple (5)
I believe the answer is:
lithe
'supple' is the definition.
(I know that supple can be written as lithe)
'many an article' is the wordplay.
'many' becomes 'l'.
'an' becomes 'i' (Roman numeral for one).
'article' becomes 'the' (the definite article in English).
'l'+'i'+'the'='LITHE'
'is' acts as a link.
(Other definitions for lithe that I've seen before include "Supple and graceful" , "Svelte" , "flex with no difficulty" , "showing great athletic ability" , "Lissome, supple" .)