backstop

(băkˈstŏpˌ)

1. Sports A screen or fence used to prevent a ball from being thrown or hit far out of a playing area, as in baseball.
2. Baseball A catcher.
3. Something that supports or bolsters.

1. To serve as a backstop for.
2. a. To support or bolster: “The firm lacks a topflight strategic-consulting arm to backstop its technology gurus” (Alex Beam).
   b. To substitute for (another) in an emergency.