The term 'SUITABLE FOR THE UPPER CRUST' can be summarized by the crossword solution POSH, which is an acronym for 'Port Out Starboard Home'. This phrase was used to describe the most luxurious cabins on ships travelling from England to India in the 19th century. It was a sign of wealth and status to have a cabin on the port side of the ship when leaving England and the starboard side when returning home. Thus, POSH became a slang term for something that is luxurious and suitable for the upper class.