The A7sus4 chord, sometimes referred to as A7sus, is a type of suspended chord. This chord is built with the notes A, D, E, and G. It is an A7 chord (A, C#, E, G) with the major third (C#) replaced by a perfect fourth (D).
Here are steps to construct it:
Start with an A Major chord, which has the notes A, C#, and E.
Then, you add the minor seventh note, G, to get an A7 chord (A, C#, E, G).
Finally, replace the third of the chord (C#) with the fourth (D). This creates a suspended 4th chord, A7sus4, with the notes A, D, E, G
Take a look below at several good A7sus shapes to practice