I am a set of three words, all with the same four letters.
First I am a type of carriage.
Then switch my middle letters, and I am a cover often useful on a diamond.
Now switch my end letters ...
When you see me, you also see hair.
What are the words?
trap = a light one-horse carriage
tarp = a canvas cover, one use is to protect a baseball diamond from rain
part = the line that divides hair, as when combing
Today's brain teaser courtesy of Braingle.com.