City's former special police after fashionable old writer (9)
I believe the answer is:
inverness
'city's' is the definition.
(I have seen 'Scottish city ' mean 'inverness' so perhaps 'city' could also mean 'inverness')
'former special police after fashionable old writer' is the wordplay.
'former special police' becomes 'SS' (Schutzstaffel in Nazi Germany).
'after' says to put letters next to each other.
'fashionable' becomes 'in' (in can mean fashionable or trendy).
'old writer' becomes 'Verne' (Jules Verne, 1828-1905).
'in'+'verne'='inverne'
'ss' put after 'inverne' is 'INVERNESS'.
(Other definitions for inverness that I've seen before include "Scots Highlands city" , "Highland region town" , "northern city" , "Highland city" , "Scottish Highlands city" .)