Answer:
What word has kst in the middle, in the beginning, and at the end?
What is made of wood, but can't be sawed?
I help engines spin and pants stay up.
There's not a kingdom on the earth I haven't traveled over and over and though I know not whence my birth yet when I come you know my roar. I through the town do take my flight and through the fields and meadows green and whether it be day or night I neither am nor can be seen.
I have a name that's not mine and no one cares about me in their prime. People cry at my sight and lie by me all day and night.
Though not a plant, has leaves. Though not a beast, has spine. Though many wouldn't need this thing, It's more valuable than wine.