Answer: cloaca

AnswerCrossword Clue
CLOACANational Health plan to follow McAloon (nothing odd about that), leading to passage Egg must go through (6)
CLOACA... Maxima (early Roman sewer)
CLOACAAncient sewer
CLOACAZoological cavity
CLOACAMouth's opposite, in birds and reptiles
cloacaa. the common cavity into which the intestinal, urinary, and generative canals open in birds, reptiles, amphibians, many fishes, and certain mammals b. similar cavity in invertebrates
cloacaa sewer
cloacasewer, esp. an ancient sewer