Hello and welcome! As lordloss has mentioned, that clear protector is mylar. It's found on tons of games, especially ones made in the mid 80s.

Since your game has a mylar protector, you'll want to stay away from any cleansers that contain petroleum distillates--as they soften the glue beneath the mylar around the edges, and may cause it to peel. I've personally moved to using straight Naphtha from the hardware store for most cleaning. It's cheap, accessible, and very gentle. I use straight Mother's non cleaner carnauba wax to keep things protected. Most people use Novus products around here, and they're fine, but Novus 2 is abrasive (but it'll really buff up mylar well), and not recommended anymore for routine cleaning. Avoid Novus 3. It's not something I generally think many people use.

Here are a few resources to get you started. They'll be your bible.

https://pinside.com/pinball/forum/topic/cleaning-and-waxing-pinball-machines-vids-guide
http://www.pinwiki.com/wiki/index.php?title=General#Recommended_Supplies
http://www.pinwiki.com/wiki/index.php?title=Rubber_and_Rubber_Kits

And as a bonus (especially if you're looking to purchase more games):
https://pinside.com/pinball/forum/topic/how-to-not-get-ripped-off-in-pinball-vids-guide