Preventative measure quashed by jury rejecting case associated with settlement (5)
I believe the answer is:
urban
'associated with settlement' is the definition.
'preventative measure quashed by jury rejecting case' is the wordplay.
'preventative measure' becomes 'ban' (measure which aims to prevent the use of something).
'quashed by' means one lot of letters go next to another (some letters go on top of or 'quash' others).
'rejecting case' means to look at the middle letters (remove the outside letters forming the word's case).
The middle letters of 'jury' are 'ur'.
'ban' after 'ur' is 'URBAN'.
(Other definitions for urban that I've seen before include "built-up area?" , "Relating to cities" , "Name adopted by eight popes: built-up" , "away from the country?" , "Relating to a densely populated area" .)