Mountain lion, cougar (4)
I believe the answer is:
puma
I believe this clue is a double definition.
'mountain lion' is the first definition.
(I know that mountain lion can be written as puma)
'cougar' is the second definition.
(I know that cougar can be written as puma)
(Other definitions for puma that I've seen before include "International rugby player" , "back from Argentina" , "Cougar" , "Large Am. wild cat" , "American wildcat" .)