Entrenched (4-2-3-4)
I believe the answer is:
dyed-in-the-wool
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">entrenched</span>' is the definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(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" .)