little bar at the beginning of a one-staff-system

[Rafael Arndt]

There is a tiny estatical detail I would like to change, but found out nowhere how to do it:

I would like to have a bar at the beginning of the system here:

 

{ a }

%like here:
\new TabStaff { a }

%or here:
<<
{a}
{b}
>>

 

Do you think there is a possibility or is it conceptually just not possible. I am still at the beginning of the lerning curve. But dirty hacks are also welcome if nothing else is available.

 

Thanks alot, Rafael.