Who is the clerk in charge of handling the item with the highest amount of extended price?
clerk refers to o_clerk; the highest amount of extended price refers to max(l_extendedprice)
SELECT T1.o_clerk FROM orders AS T1 INNER JOIN lineitem AS T2 ON T1.o_orderkey = T2.l_orderkey ORDER BY T2.l_extendedprice DESC LIMIT 1