Answer:

baseline

Answer	Crossword Clue
BASELINE	Route from home to first
BASELINE	Route for some runners
BASELINE	Set of values used for comparison or control

BASELINE	Tennis server's spot
BASELINE	Runner's path
BASELINE	Path to home
BASELINE	Side of a diamond.
BASELINE	Where Sedgman serves.
BASELINE	Part of a diamond.
BASELINE	Part of the diamond.
BASELINE	Where Althea serves.

BASELINE	Tennis-court limit
BASELINE	Part of a tennis court
BASELINE	Runner's route
BASELINE	Standard of comparison