Also, have an in with. Acquire (or have) influence with someone in authority. For example, The only way they'll allow us to film the play is if we get an in with the director, or We should have no problem, since Dad has an in with the inspector. This idiom employs the noun in the sense of “an introduction to someone of power, fame, or authority,” a usage dating from the 1920s.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.