Foolishly I am rude about old city's writer (2,7)
I believe the answer is:
du maurier
'writer' is the definition.
(du maurier was a playwright)
'foolishly i am rude about old city's' is the wordplay.
'foolishly' is an anagram indicator.
'about' indicates putting letters inside.
'old city' becomes 'ur' (ancient city state).
'i'+'am'+'rude'='iamrude'
'iamrude' is an anagram of 'dumaier'.
'dumaier' going around 'ur' is 'DU MAURIER'.
(Other definitions for du maurier that I've seen before include "who gave birth to Rebecca" , "Author of Jamaica Inn" , "Writer" .)