I prefer to avoid blending clear, which means on a quarter you have to scuff and shoot both quarters and the roof, so I can understand you wanting to avoid that.
You don't say what type of clear you're using, but I'd imagine each manufacturer has some type of blending solvent.
I use Sherwin-Williams products. The blend solvent is BS10. You used to have to use two guns (one for the clear, one for the BS10), but now they have it in a rattle can.
The process is to shoot one coat of clear on the repair area, then come back with a second coat that blends into the area around the repair area. (I shoot wet-on-wet second coat immediately following the first). Then, immediately shoot the blend area with BS10, which then melts the new clear into the existing clear.
Check with the place that sold you the clear to see if they have a blending solvent, and make sure you get the product data sheet.