London district where no one returns around cocktail time (9)
I believe the answer is:
islington
'london district' is the definition.
(Islington is a borough of London)
'no one returns around cocktail time' is the wordplay.
'no one returns' becomes 'ion' (I can't justify this - if you can you should give a lot more credence to this answer).
'around' is an insertion indicator.
'cocktail' becomes 'sling' (sling is a type of cocktail).
'time' becomes 't' (abbreviation).
'sling'+'t'='slingt'
'ion' enclosing 'slingt' is 'ISLINGTON'.
'where' is the link.
(Other definitions for islington that I've seen before include "part of capital" , "part of London?" , "Area of northeast London" , "North London area" , "NE London borough" .)