Use green light as a noun referring to the traffic signal or something representing permission to proceed. Use green-light -- hyphenated -- as a verb meaning to give permission to proceed. Mr. Rewrite bases this call on Merriam-Webster OnLine and Dictionary.com.
So Yahoo! should say that doctors have given Patrick Swayze a green light to appear in this TV show. It also could say doctors have green-lighted the move.
Mr. Rewrite isn't in love with green-light as a verb. It comes across as bureaucratic.