You're not too far off with what you got; try this out
SELECT Distinct c.Cust_ID
FROM Customer c
INNER JOIN Has h ON c.Cust_ID = h.Cust_ID
WHERE Cust_ID NOT IN (SELECT Cust_ID FROM Take)
You may be able to get away with this one as well
SELECT Distinct Cust_ID
FROM Has
WHERE Cust_ID NOT IN (SELECT Cust_ID FROM Take)