Answer:
What kind of dog keeps the best time?
I am a word with 5 letters. Bold are the first; true are the second; playful are the third; clever are the fourth; forceful are the fifth.
When you buy me I am costly, but the only use I have is hanging only. What am I?
I work when I play and play when I work. What am I?
I build up castles. I tear down mountains. I make some men blind, I help others to see. What am I?
It has no top or bottom, but it can hold flesh, bones, and blood all at the same time.