1 arrangement, system, organization, layout, regime, structure, make-up, composition, framework, frame, construction; conditions, circumstances:
This set-up of interlocking directorships makes it difficult to see who answers to whom and who owns what. What, exactly, is the set-up between you and Eustace?
2 prearrangement, trap, Slang put-up job:
As soon as I saw the police car, I knew we had walked into a set-up.