Slightly different. I want to select a portion of the recording that I want to keep, then delete the rest.

What I have been doing is to select what I want, cut it, then select the whole track, delete it, then paste back the cut section at the start of the track.

Would be easier to be able to just select what I want, the 'crop to selection' like I do in Gimp when dealing with images, or failing that, select what I want, invert the selection, then cut'n'close the gaps.