Well-established home, crumbling, finally came down (9)
I believe the answer is:
ingrained
'well-established' is the definition.
(thesaurus)
'home crumbling finally came down' is the wordplay.
'home' becomes 'in' ('he's home' can mean 'he's in').
'finally' indicates one should take the final letters.
'came down' becomes 'rained' (raining is a kind of coming down**).
The last letter of 'crumbling' is 'g'.
'in'+'g'+'rained'='INGRAINED'
(Other definitions for ingrained that I've seen before include "Dine in rag (anag.)" , "Deep-dyed" , "Deep-rooted" .)