Greta Thunberg's latest piece on carbon unconfined (5)
I believe the answer is:
garbo
'greta' is the definition.
(Greta Garbo)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for garbo that I've seen before include "Swedish-born actress" , "Famous film actress" , "Greta -, Swed. actress" , "film-star" , "Swedish actress born Greta Gustafsson" .)