Incredibly rare cute animal (8)
I believe the answer is:
creature
'animal' is the definition.
(I know that animal can be written as creature)
'incredibly rare cute' is the wordplay.
'incredibly' indicates anagramming the letters.
'rare'+'cute'='rarecute'
'rarecute' with letters rearranged gives 'CREATURE'.
(Other definitions for creature that I've seen before include "Living being" , "Animal as distinct from human being" , "Any organism with voluntary movement" , "Life's little pleasures!" , "Animal or beast" .)