zagrepsti

1. to scratch; to scrape
   Mačka me je zagrebla po ruci. — The cat scratched my arm.
   Neko mi je zagrebao vrata na kolima. — Someone scratched my car door.
2. (+ površinu) to scratch the surface
   Ovim tekstom smo samo zagrebli površinu problema. — With this article we've only scratched the surface of the problem.

The variant "zagrebati" is more common.