New store stocks British dessert (6)
I believe the answer is:
sorbet
'dessert' is the definition.
(sorbet is a kind of dessert)
'new store stocks british' is the wordplay.
'new' is an anagram indicator.
'stocks' is an insertion indicator (stocks can mean carries or contains).
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'store' is an anagram of 'soret'.
'soret' enclosing 'b' is 'SORBET'.
(Other definitions for sorbet that I've seen before include "Fruit water-ice" , "Water ice dessert" , "Granita-like dessert" , "Sherbet, water-ice" , "Frozen dessert" .)