Clothing design is usually referred to as "Fashion design" in Engpsh.

The term "Fashion" comes from the French word "mode" which means "a prevaipng custom or style of dress." The term "design" refers to the creation of a plan or sketch to guide the creation of an object, in this case clothing.

Examples:

She's studying fashion design in Paris to become a famous designer.
(她在巴黎学习服装设计，以便成为著名的设计师。)
He's been working as a freelance fashion designer for five years now.
(他现在已经做自由职业服装设计师五年了。)
The fashion show showcased the latest designs from the most talented designers in the industry.
(时装秀展示了该行业最有才华的设计师的最新设计。)