One in Sweden's ready for a drink (3)
I believe the answer is:
Here is my best explanation:
'a drink' is the definition.
(I've seen this in other clues)
'one in sweden's ready' is the subsidiary indication.
'one' becomes 'i' (roman numeral).
'in' is an insertion indicator.
'sweden's ready' becomes 'kr' (kronor, Swedish currency**).
'i' placed inside 'kr' is 'kir'.
'for' is the link.
(Other definitions for kir that I've seen before include "White wine and cassis", "Wine with blackcurrant", "Blackcurrant drink", "Cassis-flavoured wine", "Mixture of white wine and cassis", "White wine with blackcurrant syrup", "Cocktail", "Wine and cassis drink" and "Drink of white wine and cassis".)