From Longman Dictionary of Contemporary Englishbackstreetback‧street1 /ˈbækstriːt/ adjective [only before noun] SCLILLEGALbackstreet activities are done in a secret or illegal way, and are often done badly a backstreet abortion
Examples from the Corpus
backstreet• A hot new pachinko machine from a backstreet maker in Osaka has taken the underworld by storm.backstreetbackstreet2, back street noun [countable] a small quiet street that is away from the main part of a townExamples from the Corpus
backstreet• The other provides amazingly quick service - from an incomplete concrete house frame in a backstreet.• Three beer-befuddled construction workers played softball with my head in a backstreet on the mistaken assumption that I was Tom Tunney.• Frankie had left home and was now living in lodgings in a little backstreet near the pub they were sitting in.• One hour later the sonorous tones of Dame Melba's singing resonated through a little backstreet near the river.• From there, a quiet backstreet led to the rear entrance of her apartment block. 