Problem with Conditional Statement

I'm trying to get it so whenever the object is clicked it reduces in opacity by 10% each time, and if it gets to 10% and it's clicked again it stays at 10% instead of going to 0

I got it to keep going down in opacity fine I just don't know the code to keep it from going lower. this is what I have so far

function fadeOut(e:MouseEvent):void {

instrument.alpha -= .1;

}

if (instrument.alpha<.1) {

instrument.alpha = .1

} else {

instrument.alpha -= .1;

}