Ducks circle outskirts of small city (4)
I believe the answer is:
oslo
'city' is the definition.
(capital of Norway)
'ducks circle outskirts of small' is the wordplay.
I cannot quite understand how this works, but
'circle' could be 'o' (O is a circle) and 'o' is found in the answer.
'of' could be 'o' and 'o' is found in the answer.
'small' could be 's' (abbreviation - e.g. clothes size) and 's' is present in the answer.
A single letter 'l' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
(Other definitions for oslo that I've seen before include "Former Christiania" , "foreign port" , "Norwegian city, formerly Kristiania" , "City in Norway" , "Northern city" .)