uspon

1. (up a mountain) ascent; climb
   Uspon na vrh trajao je četiri sata. — The climb to the summit took four hours.
2. rise
   Njegov uspon u firmi bio je veoma brz. — His rise in the company was very fast.
   Turizam je u usponu poslednjih godina. — Tourism has been on the rise in recent years.
3. (of a road) uphill slope; incline
   Posle mosta počinje strm uspon. — A steep incline begins after the bridge.

The phrase "biti u usponu" means "to be on the rise".