Crossword Puzzle Sphere of competition

Clue: Sphere of competition

Office competition, often (RATRACE with 7 letters)
Some offroad bike competitions (BMXRACES with 8 letters)
Elected official straight from a Fox singing competition? (XFACTORIN with 9 letters)
Person with the biggest office (BOSS with 4 letters)
Post office gizmo (DATER with 5 letters)
Vote into office (ELECT with 5 letters)
Oak offering (SHADE with 5 letters)
Olds offering (ALERO with 5 letters)
Physics dept. offering (ASTR with 4 letters)
Dear business offerings? (SWEETHEARTDEALS with 15 letters)