Since it always happens in the same part of the pedal cycle, it is not a chain or rear wheel/derailleur problem. They tend to move in and out of phase with the pedals.

There's a slight chance it is coming from somewhere on the bike totally unrelated to the pedal/drive train and clicks because of the bike rocking when you pedal. Try rocking the bike a bit while coasting without pedalling and see it happens.

More likely, it is a pedal, crank, bottom bracket or shoe problem,

Could be a defective pedal...that happened to me with a Shimano A520. It started clicking a few months after I got it. Try pedalling with just one foot, then the other and see if still happens. My LBS mechanic said if a click happens at the top of the left foot cycle, you might have a loose crank on the right. Grab both cranks with your hands, hold one still and try to jerk the other backwards and forwards to see if they move relative to each other.

Hope this helps