Entrenched local features finish mice off (7)
I believe the answer is:
endemic
'entrenched local' is the definition.
'endemic' can be an answer for 'local' (I've seen this before). I am not sure about the 'entrenched' bit.
'features finish mice off' is the wordplay.
I cannot quite see how this works, but
'finish' could be 'end' (synonyms) and 'end' is found in the answer.
an anagram of 'mice' is 'emic' which is within the answer.
This accounts for all the letters.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for endemic that I've seen before include "Peculiar to local area" , "(Of a disease) regularly found in a certain area" , "Men dice in way commonly found in country or place" , "Native to (med.)" , "Belonging to a particular area" .)