Entrenched (4-2-3-4)
I believe the answer is:
dyed-in-the-wool
'entrenched' is the definition.
(thesaurus)
This is the entire clue.
(Other definitions for dyed-in-the-wool that I've seen before include "Fixed in one's opinions or attitudes" , "Fixed and uncompromising" , "Inveterate - they do lie down (anag)" , "Unchanging in a particular belief" , "Retain" .)