Beast pale then revitalised (8)
I believe the answer is:
elephant
'beast' is the definition.
(elephant is a kind of beast)
'pale then revitalised' is the wordplay.
'revitalised' is an anagram indicator.
'pale'+'then'='palethen'
'palethen' anagrammed gives 'ELEPHANT'.
(Other definitions for elephant that I've seen before include "African or Inidan pachyderm" , "Pachyderm hunted for ivory" , "Large animal found in the plane?" , "bigger one from two continents?" , "Source of ivory" .)