Side-lining

noun
1.
a line at the side of something.
2.
a business or activity pursued in addition to one’s primary business; a second occupation.
3.
an additional or auxiliary line of goods:
a grocery store with a sideline of household furnishings.
4.
Sports.

either of the two lines defining the side boundaries of a field or court.
sidelines, the area immediately beyond either sideline, where the substitute players sit.

5.
sidelines, the position or point of view taken by a person who observes an activity or situation but does not directly participate in it.
verb (used with object), sidelined, sidelining.
6.
to render incapable of participation, especially in anything involving vigorous, physical action, as a sport:
An injury to his throwing arm sidelined the quarterback for two weeks.
noun
1.
(sport) a line that marks the side boundary of a playing area
2.
a subsidiary interest or source of income
3.
an auxiliary business activity or line of merchandise
verb (transitive)
4.
to prevent (a player) from taking part in a game
5.
to prevent (a person) from pursuing a particular activity, operation, career, etc