Clever is a dark-green colored alicorn who is usally at his home playing video games or setting record-breaking high scores on arcade machines in Las Pegasus (he lives in a penthouse suite in the Las Pegasus area, so it's not far from where he lives).
Clever has been seen helping Berry Punch time and time again, and is Berry's official babysitter for her daughter, Ruby Pinch. He's also helped Berry with her alcoholism, and while his attempts at stopping her have been unsuccessful, he has slowed Berry's alcohol intake by a large degree.
Oddly enough, even though he was born as an alicorn, Clever has no blood relations to any Canterlot royalty. However, he was born into a rich family (which is how he managed to get a penthouse suite in Las Pegasus to live in), and he's written that off as the reason for his birth as an alicorn.
Clever DOES know Princess Twilight Sparkle personally, though. While not an Element of Harmony, his shows of pure luck on the Las Pegasus strip has made Twilight take him on adventures with the Mane 6. He's been nicknamed "Element of Luck" by the Mane 6, and that nickname has even been adopted by Celestia, Luna, Cadence and Shining Armor (jokingly, of course, as Clever doesn't actually have an Element of Harmony).
He is almost never seen without his trademark green polo t-shirt on. Even though most ponies don't wear clothes, Clever doesn't like the idea of being naked in public. He gets a bit uncomfortable when asked to take it off.
Clever has a mild case of cynophobia (the fear of dogs). While he doesn't go into a full-blown panic attack, he does hide behind a form of cover when he sees a dog. Applejack has to keep Winona on a very short leash whenever Clever visits Sweet Apple Acres so he doesn't run into Apple Bloom's bed to hide (AJ's had it happen before, and Apple Bloom was unfortunately in her bed at the time)!