(informal) a conspiracy to blame someone for an action when they are actually innocent, i.e. a plot to incriminate or frame someone or the actions involved in executing such a plot;
e.g. They established a frame-up by which they would not be suspected of the crime.
(noun)
(informal) an action or crime for which one is falsely blamed (framed);
e.g. The robbery was a frame-up to get her arrested.