Prim, quiet and rather uncivil (7)
I believe the answer is:
prudish
'prim' is the definition.
(synonyms)
'quiet and rather uncivil' is the wordplay.
'quiet' becomes 'sh' (both can be said to tell someone to be quiet).
'and' means one lot of letters go next to another.
'rather uncivil' becomes 'prudi' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'sh' put after 'prudi' is 'PRUDISH'.
Can you help me to learn more?
(Other definitions for prudish that I've seen before include "not liking anything too hot!" , "Having extreme propriety, easily shocked by sexual matters" , "Strait-laced" , "Prissy" , "Excessively prim" .)