The 'industry' group
These nouns refer to a field of work or activity. The first noun indicates what that field is.
business (music) circles (fashion) industry (car) line (hairdressing) sector (service) trade (tourist) world (art)
Since 1991 he has been trying to engineer a revolution in the car industry.
Do you know anybody who's in the hairdressing line?
Humphries says the best opportunities are related to continued growth in the service sector.