Answer:
What has three ways out and just one way in?
You’ll have me at night and if you remove the first letter I denote the top, such as on a train
I can ruin your day, or darken your life. And while I'm expected, I'm never alright. I'm bad for business, and worse for your hair. Wherever I am, there's something not there.
My first is an insect; my second is a border; my whole puts the face in a tuneful disorder.
When the horse strokes the cat, the wood begins to sing.
What body part is pronounced as one letter, but written with three, only two different letters are used?