Interest in British silver (3)
I believe the answer is:
bag
'interest in' is the definition.
(I've seen this before)
'british silver' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'silver' becomes 'Ag' (Ag is the chemical symbol for silver).
'b'+'ag'='BAG'
(Other definitions for bag that I've seen before include "Piece of luggage" , "Flexible container for shopping" , "Container for carrying thing" , "Secure" , "Pouch" .)