šljaka

1. colloq. work; grind
   Sutra rano idem na šljaku. — I'm off to work early tomorrow.
   Ova šljaka na gradilištu me ubija. — This grind on the building site is killing me.
2. slag; cinder
   Staza na stadionu bila je posuta šljakom. — The track at the stadium was covered with cinder.
3. (in tennis) clay; clay court surface
   Voli da igra na šljaci. — He likes playing on clay.

In the sense "work" the word is colloquial; the related verb šljakati means "to slog".