user: Question: How many entries are there for weight when the winner is 1st - Defier and venue is Randwick?
Columns: ['Result', 'Date', 'Race', 'Venue', 'Group', 'Distance', 'Weight (kg)', 'Time', 'Jockey', 'Winner/2nd']
Types: ['text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Won', '03 Aug 2002', 'Missile Stakes', 'Rosehill', 'G3', '1100 m', '57.5', '1:03.53', 'D. Beadman', '2nd - Ancient Song']
SQL:

assistant: SELECT COUNT("Weight (kg)") FROM "Table" WHERE "Winner/2nd" = '1st - Defier' AND "Venue" = 'Randwick';