All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
If the work which you are doing now involves Riba (interest and/or usury) as you mentioned, then you are obliged to leave it.
As regards working in fashion design, in principle this is permissible but since it is predominant that these fashion clothes will be used in what is religiously forbidden, like women wearing them without covering their ‘Awrah (parts of the body that must be covered in Islam), then it is not permissible for you to take this job unless you are in a dire necessity, like for the purpose of earning your sustenance and the like. In which case, it becomes permissible for you to do this job due to the dire necessity. However, as soon as you find another permissible job, you are obliged to leave it immediately.
Allaah Knows best.