Possible Clues:

• Witches' brew necessity
• Pet in a 51-Down
• In water one might get on to be a scientist
• Amphibian - a Ken Livingstone pet?
• Amphibian that can regrow an appendage
• 4 behind 23 and 6 hearing old sovereign?
• Salamander's pond cousin
• Semiaquatic lizard
• See 8
• Little lizard