understudy
HRLv.4 (900)noun
Definition
a person trained to take over another's role if that person is unavailable
Examples
An understudy for each key task prevented any gap in coverage.
As the manager's understudy, he sat in on meetings for a year.
Collocations
act as understudytrain an understudya capable understudy
Paraphrase
backupstand-in