Panthera onca (6)
I believe the answer is:
jaguar
'panthera onca' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for jaguar that I've seen before include "Large spotted cat" , "Big cat of tropical America" , "Big cat; make of car" , "S.Amer. wild cat" , "Spotted feline and posh car" .)