Plan or pattern (6)
I believe the answer is:
design
I believe this is a double definition.
'plan' is the first definition.
(I know that plan can be written as design)
'pattern' is the second definition.
(I know that pattern can be written as design)
(Other definitions for design that I've seen before include "Conceive" , "Preliminary sketch or plan" , "Prepare a drawing or model" , "Pattern - plan" , "Devise, create, make out a plan" .)