Here's how you can enable the one-click to minimize feature in Ubuntu 14.04.
1. Open a terminal window.
2. Type in the following commands then hit Enter:
sudo apt-get install
sudo apt-get install compizconfig-settings-manager
3. In the Unity Dash type in CCM to open CompizConfigSettings Manager.
4. Go to Unity plugin.
5. Click the "Minimize Single Window Applications" check box.
Minimize on click has landed in Ubuntu 14.04 Trusty Tahr and it is disabled by default. You can enable it from Compiz settings manager.More at Noobs Lab
Additional Ubuntu Resources