The phrase "an extra role" is correct and usable in written English.
It can be used when referring to an additional position or function that someone takes on, often beyond their primary responsibilities.
Example: "In addition to her main duties, she has taken on an extra role in the project to help with coordination."
Alternatives: "a supplementary role" or "an additional role".
Gary Cohn, the firm's president, will take on an extra role as head of the business-standards committee.
I got attached to these children; they were different to the kids in my school who don't need an extra role model in their lives because they've got so many already.
At that time, I was directing plays in Cambridge, so the following year, when they were brought back to stage Pushkin's "Boris Godunov," I was able to talk my way into an extra role — I was one of a number of poverty-stricken mendicants, with a beard, a ragged coat, and a gnarled walking stick.
In addition to playing the same role as and of introducing long-range interaction, the most different block plays an extra role of informing the algorithm that the label associated with the most different block is to be avoided.
Next time out, there'll be a line around the block of midwestern try-hards trying to bustle their way into the background of a 'pap snap' in the hopes of landing an extra role on Blacklist.
Shortly after she was commissioned the Navy decided to give her an extra role as a gunnery training ship and she entered Toulon Dockyard for the necessary modifications on 24 October 1932.
Many of these are what we would consider an extra-role; they are not required as part of employees' jobs.
OCB is an extra-role behavior but very necessary for an organization's success (Niehoff, 1993).
Everyone there seemed to be chanting for a featured extra role on Smallville, even though Smallville was cancelled seven years ago.
Many stem from Bret's fleeting appearance as an elf in The Lord Of The Rings, a non-speaking extra role with unanticipated consequences.
Although they never returned to America's Best Dance Crew as supervising choreographers, Napoleon continued to serve as a talent scout an extra role he had on the show since its inception.
