Criminal seizing top-quality pottery (7)
I believe the answer is:
faience
'pottery' is the definition.
(faience is a type of ceramic)
'criminal seizing top-quality' is the wordplay.
'criminal' becomes 'fence' (I've seen this before).
'seizing' is an insertion indicator.
'top quality' becomes 'ai' (resembles A1, informal term for top quality).
'fence' going around 'ai' is 'FAIENCE'.
(Other definitions for faience that I've seen before include "porcelain" , "ceramic ware" , "A glazed earthenware" .)