Sierra joins team to become one of many on board (5)
Inspired by today's Minute Cryptic...
Edit: Adding some clues
Definition: >!one of many on board!<
Fodder: >!Sierra (needs synonym), team (needs synonym)!<
Indicators: >!"joins", "to become" (not an anagram indicator)!<
Extra hint: >!Consider definitions of "board" beyond the surface parse!<