[up to par] or {informal} [up to scratch] or {informal} [up […]

[up to the chin in] or [in --- up to the […]

[upper crust] {n.}, {informal} The richest, most famous, or important people […]

[upset the applecart] or [upset one's applecart] {v. phr.}, {informal} To […]

[urban homesteading] {n.}, {informal} Renovation and occupation through cooperative ownership by […]

[use every trick in the book] {v. phr.}, {informal} To avail […]

[use up] {v. phr.} 1. To use until nothing is left; […]

[Vietnam syndrome] {n.}, {informal} An attitude in government circles that diplomacy […]

[wade in] or [wade into] {v.}, {informal} 1. To go busily […]

[walk on air] {v. phr.}, {informal} To feel happy and excited. […]