enter into
Participate in, take an active role or interest in, as in We had to think twice before we entered into these negotiations. [Late 1700s]
Become party to (a contract), bind oneself, as in The nations entered into a new agreement. [First half of 1500s]
Become a component, form a part of, as in Finances soon entered into the discussion. [Early 1700s]
Also, go into. Consider, investigate, as in The report entered into the effect of high interest rates, or Let's not go into that. [Mid-1500s]