Hi Paul,

First of all, you do not need to clone a web part in order to be able to define transformation you want. You can create as many instances of one particular web part as you want and each of them can use different transformation.

In terms of creating a new transformation, you can do so in Site manager -> Development -> Document types -> edit CMS.News -> Transformations -> New transformation. Moreover, you can copy and paste the definition of NewsPreviewWithSummary transformation to the new one and modify it according to your needs.

If you need more information please visit following section of Developer's guide Document types and transformations

Best regards,
Michal Legen