Article about variable ability to read (8)
I believe the answer is:
literacy
'ability to read' is the definition.
(I've seen this before)
'article about variable' is the wordplay.
'about' indicates an anagram.
'variable' becomes 'y' (algebra).
'article' with letters rearranged gives 'literac'.
'literac'+'y'='LITERACY'
(Other definitions for literacy that I've seen before include "Ability to read and write" , "I lay cert (anag.)" , "Writer's skill" , "Learning" , "education?" .)