Top style in Russian city (4)
I believe the answer is:
perm
I believe this is a double definition.
'top style' is the first definition.
(hair style)
'russian city' is the second definition.
'in' acts as a link.
(Other definitions for perm that I've seen before include "Russian city and hairstyle, in short" , "Hairdo - combination on football pools" , "Hair setting treatment; pools selection system" , "Old-fashioned haircut" , "Give a wave" .)