Builder's binder (6)

I believe the answer is:
cement
(Other definitions for cement that I've seen before include "Join firmly together" , "Union" , "Ingredient of concrete" , "Glue" , "Bond firmly" .)
I believe the answer is:
cement
(Other definitions for cement that I've seen before include "Join firmly together" , "Union" , "Ingredient of concrete" , "Glue" , "Bond firmly" .)