Playwright unknown in China? (7)
'china?' is the definition.
'playwright unknown' is the wordplay.
'playwright' becomes 'Potter' (playwright Dennis Potter).
'unknown' becomes 'y' (algebra).
'in' acts as a link.
(Other definitions for pottery that I've seen before include "Goods of fired clay", "Items made from clay", "Ceramics factory", "baked goods", "Items of fired clay".)