Use the Cenarion Lunardust on the Moonkin Stone between Mulgore and the Barrens to bring forth Lunaclaw. From there, you must face Lunaclaw and earn the strength of body and heart it possesses. Speak with Turak Runetotem in Thunder Bluff when you are done.
On land west of Taurajo in the Barrens - just before it turns into Mulgore - lies a Moonkin Stone. The moonkin are special beasts, not native to these parts. Lunaclaw, the stone's defender, will face you when Cenarion Lunardust is applied to it. Lunaclaw possesses within it a strength that you must use as one of the Claw.
You've earned the right to use this Cenarion Lunardust, [player]... now show me that you've earned the right to possess the strength of body and the strength of heart needed as a druid!