Clue: Fashionable people get new mattress (5,3)
Answer: SMART SET
Explanation: Fashionable people get new mattress (5,3)
~~I suppose this is intended to be a definition and literal interpretation, but I do not like it: it is a long time since I bought a bed, but I would have thought that a 'set' would be a mattress and box spring (or whatever they are called over the pond and elsewhere), and in any case there are many other meanings of set. 'New' for SMART is none too precise either.~~ An anagram ('new') of 'mattress.