Accustom oneself to a shattered Eastern ruin (5)
I believe the answer is:
inure
'accustom' is the definition.
(I know that inure is a type of accustom)
'shattered eastern ruin' is the wordplay.
'shattered' is an anagram indicator.
'eastern' becomes 'e'.
'e'+'ruin'='eruin'
'eruin' anagrammed gives 'INURE'.
'oneself to a' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for inure that I've seen before include "Accustom (someone) to something unpleasant" , "Harden, make accustomed to" , "Steel" , "Harden or season" , "harden attitude" .)