Possible Clues:

• Prehistoric elephant-like mammal
• Animal of a genus of extinct elephants
• Prehistoric mammal
• Pole, old fellow perceived of as a big beast
• Builder has engraved amphibian, not a huge beast
• Extinct elephant cousin
• Prehistoric beast with tusks
• Ancient beast not so mad perhaps
• Extinct mammal — man stood (anag)
• No points awarded to amateur coming back for old elephant