Definition of carriage trade in English:

carriage trade

noun

mass nounNorth American
informal
  • The wealthy clientele of a business.

    ‘determined to pursue the carriage trade, she quickly established an old-girl network’
    • ‘Later, in 1883, it became a citrus farm, and finally in 1893 a holiday destination for the wealthy passengers of the East Coast carriage trade.’
    • ‘First, doing so would raise prices, restricting flight to the carriage trade.’
    • ‘Perhaps it was because of the venue where he performed (and the carriage trade he attracted).’

Origin

With reference to people who formerly would have been wealthy enough to maintain a private carriage.