You can be complimented on any number of things. It may be the quality of your work, the speed at which you work, your consistency, or anything else. Choose the attribute that you think is most valuable to the company in this particular role. For example, working quickly may be more important for an alterations tailor; being empathetic would be more important for a fitter; and being creative would be more important for a designer.

Identify the most important attribute that fits both the company and the role you're applying for. Then think of a time when you exceeded a customer's expectations in that area.

Example answer. "A customer told me that I work extremely fast. He needed the lining in his trousers remade. I told him to come back in three days, and he told me that everyone else took a week. Because of that, he came to me for all of his tailoring needs."