Welcome to the forum, Fred.
So, are you saying that the line was sharp before you applied the clear?
Just to get a bit more info; are you using Tamiya acrylic in the bottles or lacquer in the spray can?
Either way, it may be a case of applying the clear to heavy from the start of application. For most paints and clears, it is much better to start off by lightly misting a coat or two of paint (or clear). Let it set up a couple minutes then another light coat. You should have good coverage by that time. If you need to apply another light coat and let that flash off a bit, and then apply your wet coat.
I can't be sure that this will solve your problem, but it's all I can think of. I'm not an expert painter so others may have better advice.