Pottery expert invests pound (5)
I believe the answer is:
delft
'pottery' is the definition.
(I've seen this before)
'expert invests pound' is the wordplay.
'expert' becomes 'deft' (I've seen this in another clue).
'invests' means one lot of letters goes inside another (inserted letters are invested).
'pound' becomes 'L' (the pound sign is based on an L).
'deft' placed around 'l' is 'DELFT'.
(Other definitions for delft that I've seen before include "Potter production" , "Netherlands town famous for its pottery" , "A type of earthenware" , "Dutch pottery city" , "type of pottery" .)