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 stitch up 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