Designed article stuffed with silver tissue (9)
I believe the answer is:
cartilage
'tissue' is the definition.
(cartilage is a kind of tissue)
'designed article stuffed with silver' is the wordplay.
'designed' indicates an anagram (designed with the letters).
'stuffed with' means one lot of letters goes inside another (some letters get stuffed inside).
'silver' becomes 'Ag' (Ag is the chemical symbol for silver).
'article' with letters rearranged gives 'cartile'.
'cartile' enclosing 'ag' is 'CARTILAGE'.
(Other definitions for cartilage that I've seen before include "Connective tissue in joints" , "bodily tissue" , "Tough white flexible tissue attached to bones" , "Gristle" .)