Consul regularly heading for overseas city (4)
I believe the answer is:
oslo
'city' is the definition.
(capital of Norway)
'consul regularly heading for overseas' is the wordplay.
'regularly' indicates alternate letters (regularly take one letter, leave next etc.).
'heading for' says to take the initial letters.
The initial letter of 'overseas' is 'o'.
The alternating letters of 'consul' are 'osl'.
'osl'+'o'='OSLO'
(Other definitions for oslo that I've seen before include "Northern city" , "Norwegian chief port" , "Northern capital of Czechoslovakia?" , "European capital in go-slow" , "Go solo to European capital" .)