I think I understand what you are trying to do... but maybe not.

Understanding the object is the key, if I am thinking of what you are after correctly.



If you click the embedded image here, you will see the principle handles I am going to talk about.

There are the left and right stretch handles that I think will help you. 

You will need to switch to Time-Line mode to perform this edit.

On the audio object, you can see the handles, if you left click with the mouse on the left stretch handle and hold while dragging the mouse to the right, you are virtually setting a new start point position of the audio, you can do the opposite on the right stretch handle by left clicking, holding and dragging left to create a new end point.

This will allow you to isolate just the area of music or audio (works on video as well) that you want.

Another possibility is to cut the audio.

Again, you need to be in the Time-Line Mode

Make sure just the audio is selected (audio track will be orange) then you place the play cursor at the  point in the audio you want it to start from and used the razor blade icon to place a cut marker... repeat the process for the end piece, this gives you three separate audio objects. If you just need the middle, then you can delete the first and third, now you have only the audio that you wanted.

Thing to remember is both of these will result in the same thing and both are NON-DESTRUCTIVE... this means they are not harming the original material, they are only making virtual cuts for the project, not cutting the original sample.

I hope this is what you needed, if not... let me know