The antiquarian's avowed interest is shattered (2,5)
I believe the answer is:
in ruins
I'm afraid I can't even guess how this answer relates to the clue.
Can you help me to learn more?
(Other definitions for in ruins that I've seen before include "Broken-down" , "Ramshackle" , "Wrecked" , "Effectively destroyed" , "falling apart" .)