Possible Clues:

• Zoo heavyweight, informally
• Land animal whose closest living relatives include whales
• Penultimate set from Aretha Franklin — kept tape for wallower
• Native African transported by ship, possibly
• Thick-skinned type taking fruit by Italian river
• Land animal whose closest living relative is the whale
• Mud-loving animal
• Tusked mammal
• River horse (abbr)
• Gloria, in 'Madagascar'