1.
To stitch someone up means to trick them so that they are put in a difficult or unpleasant situation, especially one where they are blamed for something they have not done. (BRIT INFORMAL)
He claimed that a police officer had threatened to stitch him up and send him to prison.
= frame, set up
PHRASAL VERB: V n P, also V P n (not pron)
2.
To ~ an agreement, especially a complicated agreement between several people, means to arrange it. (mainly BRIT INFORMAL)
Shiraz has stitched up major deals all over the world to boost sales.
= secure
PHRASAL VERB: V P n
3.
see stitch 5