Bear or hare (6)
I believe the answer is:
mammal
This clue is a double definition.
'bear' is the first definition.
(thesaurus)
'hare' is the second definition.
(thesaurus)
(Other definitions for mammal that I've seen before include "Animal of a class giving birth to live young" , "warm-blooded beast" , "Type of animal such as man" , "Milk-secreting animal" , "It's young are nourished by milk" .)