Sciurus vulgaris, arboreal rodent (3,8)
I believe the answer is:
red squirrel
I believe this is a double definition.
'sciurus vulgaris' is the first definition.
(synonyms)
'arboreal rodent' is the second definition.
(I've seen this in another clue)
(Other definitions for red squirrel that I've seen before include "Native rodent" , "denizen of the woods" , "Bushy-tailed tree rodent" .)