CREATE TABLE table_54391 ("Entrant" CLOB, "Constructor" CLOB, "Chassis" CLOB, "Engine" CLOB, "Tyres" CLOB, "Driver" CLOB, "Rounds" CLOB)

Tell me the constructor for clay regazzoni
SELECT "Constructor" FROM table_54391 WHERE "Driver" = 'clay regazzoni'
SELECT "Constructor" FROM "table_54391" WHERE "Driver" = 'clay regazzoni'