serve as a/(one's) substitute(redirected from serving as a substitute)
serve as a/(one's) substitute
To take the place or fill the purpose of someone or something else. We created these wood pellets from repurposed sawdust to serve as more a ecologically friendly substitute for other fuel sources. This is Shawna, everyone. She's going to be serving as my substitute while I'm on sabbatical.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.