Basis or foundation (7)
I believe the answer is:
footing
I believe this clue is a double definition.
'basis' is the first definition.
(I know that basis can be written as footing)
'foundation' is the second definition.
(I know that footing is a type of foundation)
(Other definitions for footing that I've seen before include "Basis, foundation" , "(Firm) basis on which something is established" , "Status - relationship" , "Plain lace" , "terms" .)