Johnny Depp in 1997 was Donnie Brasco. The movie was about the true story of an undercover cop actually living too close to the mob in 70's New York. His real name is Joseph D. Pistone, an agent of the FBI. He wrote the autobiography of which the movie is based, Donnie Brasco: My Undercover Life in the Mafia, 1988.
This is your next great idea for a Halloween costume this year. Wear it for going out or for the big Halloween party that you are planning.
The real point here is to highlight Depp's costuming in the movie scene on the party boat. He wore the classic teardrop aviator sunglasses like the Ray-Bans shown here. Now the glasses come in every color imaginable and with the important UV protection. He possibly wore the gunmetal/crystal green shade. The scene is a mob boat party and his friend Lefty is out to impress a NYC mob syndicate.
Finding the light hued leisure suit would involve a few trips to the second hand clothes store. Note that it is not white. Look for tan or taupe in order not to be mistaken for the disco dancing guy. Do not wait too long or you may come up short on completing the whole look. You have to keep an eye open for the white long collar dress shirt, 70's style.