Adhesive binding agent revolutionary as building material (6)
I believe the answer is:
gypsum
'building material' is the definition.
(material used to make plaster)
'adhesive binding agent revolutionary' is the wordplay.
'adhesive' becomes 'gum' (gum is a kind of adhesive).
'binding' is an insertion indicator.
'agent' becomes 'spy' (spy is a kind of agent).
'revolutionary' shows that the letters should be reversed in order.
'spy' written backwards gives 'yps'.
'gum' enclosing 'yps' is 'GYPSUM'.
'as' acts as a link.
(Other definitions for gypsum that I've seen before include "White mineral in cement and plaster" , "Spy mug made from this white mineral" , "Ingredient of fertilizer" , "Chalky material in plaster of Paris" , "Mineral used to make plaster of Paris" .)