Another way to make a break in the track instead of automating the volume fader is the following.
1) If you are using Reason 4 - You can use the razor tool and click in the ruler at the top of the sequencer (not in a clip, but in the ruler!)
select the razor tool, then left click and drag to the desired length (check the snap settings). All of the clips will now be selected.
You can now right click on any one of the selected clips and either choose mute clips or simply delete the clips.

OR

2)Use the left and right locators to set a desired position the go to the edit menu and click 'insert bars between locators'. (remember to check the snap settings).

Matt.

__________________
www.reason4tutorial.com
Over 9 hours of easy to follow, step by step online video tutorials that teach you everything you need to know about Propellerheads Reason 4.