Hi - you want to stretch/lengthen/shorten clips and have them behave like a varispeed (tape deck).
As ‘Likelystory’ says, many ways to actually perform the ‘stretch’ - BUT as he also implied, you need to choose your algorithm type, first…! So, look under Audio processing and functions → Pitch Shift or TimeStretch (page 404 - 412 in Cubase manual). Then, page 424 (in the Cubase manual, don’t have Nuendo), for explainations about all the different time/pitch shift algorithms available - ‘Elastique’ is the one you want, with the ‘Tape’ mode in particular.
Once you’ve chosen your algorithm, this is what will be used when you apply the ‘Sizing Applies Timestretch’ method from the arrow tool for instance.
Hope that helps,
Bob