get a foot in the door

get a/(one's) foot in the door

To have a chance to do something that could lead to further opportunities. The phrase is often used to refer to employment. An internship might not sound very interesting, but it's a great way to get your foot in the door at this company.
See also: door, foot, get
Farlex Dictionary of Idioms.

get a foot in the door

or

get your foot in the door

COMMON If you get a foot in the door or get your foot in the door, you make a small but successful start at becoming involved with an organization or a business. I really wanted to be a photographer and the only reason I took the job was because I thought it might help me get a foot in the door. Temping is a good way to get your foot in the door. Note: You can also use verbs such as have or want instead of get. The company said it issued the low bid because it wanted a foot in the door of a potentially lucrative market.
See also: door, foot, get
Collins COBUILD Idioms Dictionary, 3rd ed.

get/have a/your ˌfoot in the ˈdoor

start/have started to be accepted in an organization, a group, a profession, etc. that could bring you success: It’s difficult to get your foot in the door as a young actor without any experience. ▶ ˌfoot-in-the-ˈdoor adj.: aggressive, foot-in-the-door sales techniques
See also: door, foot, get, have
Farlex Partner Idioms Dictionary
See also:
  • a foot in the door
  • a leg in the door
  • a toe in the door
  • foot in the door
  • foot in the door, get one's
  • get a/(one's) foot in the door
  • get foot in the door
  • get/have a/your foot in the door
  • have a foot in the door
  • have a/(one's) foot in the door