I think you're probably going to have to respray the whole thing. You could scuff it up and try to blend in the area to the rest, but I'm sure it would never match. But then if you do that..the newly painted trunk wouldn't match the rest of the car..humm
The clearcoat has deteriorated and is delaminated. This has exposed the base color. Any repair is only going to be as good as the foundation it's applied to. That being said, do you really think painting over an existing problem surface is the best thing? I would think strip the panel and refinish as needed. Other methods might only be a "band aid" fix. If you're going to keep the car, do it once. Good luck Stu
Once the clear disappears, like yours did, it lets moisture get into the basecoat, which is porous paint. If you do not live in a very dry area, there's probably rust under that blue paint where the clear is gone. Spreads quickly, too!
sorry to say, the only fix is to repaint and clear the entire hood and blend paint to the left fender and clear it also.