REVERE-A desperate thief is still on the loose after trying unsuccessfully to snatch a purse Sunday from a 64-year-old woman at the Wonderland Plaza Stop and Shop.The victim was pushing a carriage down an aisle around 12:30 p.m. when the crook came out of nowhere and grabbed the purse from the top of the cart, police said.Luckily for the victim, a store employee intervened and grabbed the purse as the suspect tried to run away.The two men tugged on the purse before the employee managed to take it back from the suspect, who then ran out of the store, police said.The suspect is described as a “stocky” white male about 5-foot-9 with blue jeans and a plaid shirt.Anyone with information is asked to call Revere Police at 781-284-1212.