[Blue Bowtie]

That is a glass area of the fender, not the RIM/urethane facia, right? If it's glass and resin, it would be easy to grind, lay in cloth, and resin the repair area once the panel is brought back into the correct form/shape. The remaining surface can be built up to the correct level with fiberglass filled polyester body filler (fiberglass bondo) and glazing compound, just like any other body repair. If the fender is cracked, you almost can't do anything to make it worse which can't be undone if it doesn't go well, so long as you take care to bring the panel lines into the proper form/shape before bonding it. You may have to remove some more material in order to regain the shape before repair.

Heavily frayed or irregular cracks are often cut out and patched in with repair panels since it is far easier to maintain a good line and shape from a clean, straight edge without overfilling the repair.