Clank is technique. Do it when you want to, don't when you don't want to. If you can't clank on command (and only on command), practice until you can.
Of course, setting up your bass, the strings you have on, it, etc. all affect this. But you are in control of those things as well. I generally don't play out on really fresh strings, as they clank a bit too much - I like at least a week on strings when I play out. I also practice the week before a gig with the bass I'm going to play, so I can calibrate my technique to that bass with those strings.