A Hoop Around a Star, Also a Larry Niven Novel
Puzzle 8 of Sci-fi Universe Medium Pack
Question is: A Hoop Around a Star, Also a Larry Niven Novel
and the answer is: RINGWORLD
Word Meaning:
RINGWORLD — (science fiction) An artificial megastructure in space, consisting of a rotating ring encircling a star and having an inhabitable inner surface with gravity produced through centripetal force.
Definitions from Wiktionary.