if you feel confident, you can use this combo. It's OK but you should be careful
however, if you are not confident, I think you should use another better, lighter AV such as avast or AVG with proper settings
I think WD is a bit overrated. It's not enough to protect average users/happy clickers/default-allow users. It's not the lightest AV, doesn't have the best detection rate, almost has no behavioral blocker. The good things are that it doesn't slow down boot time and doesn't damage the PC
in order to be safe with WD, users have to learn good habits and stay alerted most of the time. Experienced users may become happy clickers in some cases, nobody is sure 100% that they never become happy clickers when their moods are elevated
in this case, a better AV is more likely to save your day
anytime, everyone should learn a bit about safe habits
if you are a brave man , than use defender. if you are a paranoid user than go for something more secure. if you like to venture out on discutable site and download sources pari defender up with zam and voodooshield , then you should be pretty ok.