Careless teenager drops new piece of furniture (7)
I believe the answer is:
etagere
'piece of furniture' is the definition.
(I've seen this before)
'careless teenager drops new' is the wordplay.
'careless' is an anagram indicator.
'drops' is a deletion indicator.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'teenager' with 'n' taken out is 'teeager'.
'teeager' with letters rearranged gives 'ETAGERE'.
(Other definitions for etagere that I've seen before include "Piece of furniture for displaying small ornaments" , "Stand of shelves" , "place for knick-knacks" , "Piece of furniture with open display shelves" , "Furniture item with shelves" .)