Information concerning class (5)
I believe the answer is:
genre
'class' is the definition.
(genre can mean a class or type)
'information concerning' is the wordplay.
'information' becomes 'gen' (gen can informally mean information).
'concerning' becomes 're' (both can mean on a particular topic).
'gen'+'re'='GENRE'
(Other definitions for genre that I've seen before include "Kind" , "Particular style of art or literature, may be green" , "Artistic or literary category" , "Category of literature" , "Style of work" .)