noun
1.
tie-up (with sb/sth) ( BrE ) an agreement between two companies to join together :
They're negotiating a tie-up with Ford.
2.
tie-up (between A and B) ( BrE ) a connection between two or more things :
a tie-up between politics and economics
3.
( especially NAmE ) a situation in which sth stops working or moving forward :
a traffic tie-up