I clone has a much smaller and weaker root system than a plant from seed. A plant from seed has a long tap root that keeps looking for water. The root span of a clone is much smaller.

Before heat wave clone roots support top growth. Now the roots can not get enough moisture to keep top alive.

Here's what I would do. Stop the ferts. Now. Wait til it gets cooler. Flush your area. This evening.

Get a large plastic jug. fill it with water. poke a small, SMALL!!! hole in the bottom. Put it at the base of your clone. Let it feed a constant flow of water to your roots (a drop a second is ok). Keep doing that until it gets cooler.

Good Luck