Headlamps

The clear lamp you're talking about is typically referred to as a "corning light". There is no straight forward way of making this lamp come on without the turn signals. It would require the installation of custom wiring with relays. If you're familiar with how to wire automotive relay systems, the easiest thing to do would be the use of the low beam headlamp circuit to energize a relay that would then activate the corning lamps.

Attached is a basic 12 volt relay diagram. In this case, you would connect terminal 86 to your low beam headlamp circuit. The corning lamps would connect to terminal 87. Terminal 30 should be connected to a fused 12 volt source such as the positive battery post and terminal 85 should be connected to chassis ground or the negative battery terminal.