A 7alt, 1st inversion (C# in the bass)
Also written as A7alt/C#.
Notes, from the bass up
C# (bass)GBbB#FA
The same notes as A 7alt (C#, G, Bb, B#, F and A), rearranged so C# is the lowest note. Use it to move between chords with smaller jumps across the keyboard.