Coat ripped, twice defaced by fabulous beast (7)
I believe the answer is:
unicorn
'fabulous beast' is the definition.
(I've seen this before)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for unicorn that I've seen before include "Mythical one-horned creature" , "Imaginary creature with one horn" , "Mythical animal with one horn" , "Fabulous beast like horned horse" , "that's fabulous" .)