Small, Aquatic, Swimming Mammal With a Duck Bill
Puzzle 18 of Alliteration Piece of Cake Pack
Question is: Small, Aquatic, Swimming Mammal With a Duck Bill
and the answer is: PLATYPUS
Word Meaning:
PLATYPUS — A semiaquatic monotreme from eastern Australia with a bill resembling that of a duck, that has a mole-like body, a tail resembling that of a beaver, a waterproof pelt, and flat webbed feet (Ornithorhynchus anatinus).
Definitions from Wiktionary.