CREATE TABLE table_56212 ("Number" FLOAT, "Locomotive type" TEXT, "Wheel arrangement" TEXT, "Builder" TEXT, "Entered Service" FLOAT, "Withdrawn" FLOAT)

When did the tom smith built train enter service with a number under 7007?
SELECT AVG("Entered Service") FROM table_56212 WHERE "Builder" = 'tom smith' AND "Number" < '7007'
SELECT AVG("Entered Service") FROM "table_56212" WHERE "Builder" = 'tom smith' AND "Number" < '7007'