Looks like an A7 without the 5th (E). The jazzers like to break up and reaarange chords, often ommiting notes. The first note to go in any chord is usually the 5th as it's considered by some to be superfluous.
The notes for this sucker are (A C# G A). That gives you the 1st, 3rd and b7th. The 1st (A) tells us were in A, the 3rd (C#) tells us it's major (as opposed to minor) and the b7th (G) tells us it's a dominant 7 (A7).
The 5th (E) really just reinforces the key we're in. In this cse, the A.
Anyway, yeah -- A7.