Reptile that can reach up to 10 feet in length

MONITORLIZARD

This large, intelligent lizard is often kept as an exotic pet and thrives near water.

This clue describes a large reptile known for its impressive size, with some species growing up to 10 feet long. The answer is "MONITORLIZARD," a type of lizard that includes well-known varieties like the Komodo dragon. The name comes from their habit of standing on hind legs to "monitor" their surroundings, though the clue itself is straightforward with no wordplay. If you picture a big, scaly reptile with a long tail, this fits perfectly.