I do not see a clamp or foreign object in the photo. The dark curved area appears to be a skin fold/crease in the pubic-groin area, with some darker pigmentation that can occur from friction, moisture, shaving, or normal skin variation.

I cannot diagnose a lump or skin condition from one photo. Get checked soon if there is a distinct new lump, pain, redness/warmth, drainage, rapid growth, or it persists longer than 2 weeks. Seek urgent care for severe pain, fever, vomiting, or a swollen testicle. The NHS guidance on lumps advises assessment for a persistent, enlarging, painful, red/hot, hard, or testicular lump.

That photo shows a raised, red, tender-looking bump in hair-bearing pubic skin. It most resembles an inflamed ingrown hair/follicle, a boil (furuncle), or an inflamed skin cyst. It does not look like a clamp.

Do not squeeze, pop, cut, or shave over it. Use a warm, clean compress for 10 to 15 minutes, 3 to 4 times daily, keep the area clean and dry, and wear loose underwear. The NHS boil advice also advises against picking, squeezing, or piercing boils.

Because it is red and raised in the groin area, arrange an in-person check within the next day or two, especially if it is painful or growing. Get urgent care today if you develop fever, rapidly spreading redness, severe pain, pus, red streaks, or swelling of the penis/testicle.