New World marsupial (7)
I believe the answer is:
opossum
'new world marsupial' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for opossum that I've seen before include "American and Australian marsupial, often with the first letter dropped" , "Large marsupial" , "American tree-dweller" , "American marsupial with prehensile tail" , "New World marsupial" .)