"The clap" is a slang term for gonorrhea (a sexually transmitted disease). We cannot omit the article "the" with this expression.

"The clap" is a slang term for gonorrhea, a sexually transmitted disease.

She caught the clap and got the shot.

We cannot omit the article "the" with this expression.

Have you ever had the clap?

The clap can produce a burning sensation in men.

Should you use "a" or "an" before STD? (Sexually Transmitted Disease)

In standard English and/or formal situations, we use the term "gonorrhea" (with no article) instead of "the clap".

People who have gonorrhea should also be tested for other sexually transmitted diseases.

Using "a" or "the" before names of diseases