Many an article is flexible (5)
I believe the answer is:
lithe
'flexible' is the definition.
(I've seen this before)
'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 "Elastic" , "Slim and supple" , "light" , "Don -, opera by Verdi" , "quick to move" .)