Everything British in miniature chest of drawers (7)
I believe the answer is:
tallboy
'chest of drawers' is the definition.
(tallboy is a kind of chest of drawers)
'everything british in miniature' is the wordplay.
'everything' becomes 'all' (all things).
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'in' means one lot of letters goes inside another.
'miniature' becomes 'toy' (synonyms).
'all'+'b'='allb'
'allb' placed inside 'toy' is 'TALLBOY'.
(Other definitions for tallboy that I've seen before include "Piece of furniture made by lofty youth" , "Type of chest of drawers" , "Two-part chest of drawers" , "Item of furniture" , "Big chest of drawers" .)