Means to give a room a quick clean and sort so it looks presentable, not necessarily deep-scrubbed. You’ll hear Give it a tidy up when someone’s coming round and you need to hide the chaos fast. Fun side note: in Wales, tidy on its own can mean great or lovely, which confuses outsiders brilliantly.
"Give the lounge a tidy up, your nan’s on her way. It’s tidy. Babe, there’s a crisp packet under the cat and three mugs growing their own ecosystem on the windowsill"