“A” string retainer

You have to.

 

Don't know if they're generally available, but Fender makes the "A" string retainer that attaches to the tuner. I think they come on the Am Std or Deluxe 5-strings ( maybe the 4's too).

 

They're not generally available. Only as repair parts or included on a bass. (I emailed Fender and eventually got a reply)

Another choice is to replace the original retainer with a 3- string aftermarket retainer.

 

I think the latest version is a different washer under the nut that has an arm for the string to go under. I have never seen them available. I think the first version was a screw-in with a hook on top. With the proper string winding on the tuner post, I have never had a issue with the A string. I am surprised no aftermarket piece has come on the market. Maybe it's just too small to make it profitable.
Rocky