Clark's skeletal hydraulics issues
I'm reading the question as saying there's too little pad gap and it's causing rub as well as lever travel that seems too tight/short/firm.

The first thing to do with any problem of this nature is to try pushing the pistons back in (after cleaning the outside if needed) and re-adjusting the caliper centering. Pistons that have somehow gotten pushed out too far can cause all the problems you're having. Some good tools to do this are a tire lever or an 8mm box wrench against the piston faces directly, or a degreased cone wrench, table knife, etc against the pads. It can help to slightly lubricate the pistons first with whatever fluid the system uses (DOT 3/4 fluid in this case) after cleaning them, in case drag when passing through the caliper seals is causing retraction issues. 

Overfill per se is not usually the problem, although it is possible to overfill a brake using an incorrect bleed block. What usually gets mistaken for overfill is DOT fluid expanding due to absorbing water that makes it past the seals, because it absorbs water out of the air very readily. Most or all DOT fluid brakes seem like they do this to some extent over time, or at least can. (Mineral oil doesn't do this, which is one of its advantages). It's extremely common, for example, that a new bike that's been sitting warehoused halfway through a model year has this symptom when unboxed for assembly. When Juicy 3s were one of the most commonly specced brakes it seemed like half of them had this out of the box.

If you observe that the pistons can't be pushed back in fully on a DOT fluid brake, fluid expansion due to water contamination is the first thing to suspect.

The simple option is to "burp" a little fluid out by removing and putting aside the pads, putting a rag up to the caliper bleed port, slightly opening the port, and resetting the pistons with the port open (again cleaning/lubricating the pistons first as needed). Some fluid will come out, which the rag is there to soak up before it makes a mess. Close the bleed port quickly when you're done of course. This usually works fine for all intents and purposes. You are reducing the boiling point of the brake fluid every time you do this as well as increasing its compressibility, both of which could hypothetically make some kind of meaningful difference at some point, but we're really talking about a very small amount of water. You also shouldn't try this if you're not prepared to bleed the brake in case something goes wrong. I'll add the disclaimer that I haven't actually done this on Clark's brakes, only on many, many Avid/SRAM brakes. Wear gloves and eye protection.

You could also replace all the fluid, which is the safer and technically correct path if water contamination is suspected.