Fabricate (7)
I believe the answer is:
concoct
'fabricate' is the definition.
(concocting is a kind of fabricating)
This is all the clue.
(Other definitions for concoct that I've seen before include "Invent, devise" , "Invent (a story/plan)" , "Fabricate" , "cook" , "Invent (a story)" .)