The phrase 'plan a robbery' is correct and can be used in written English.
For example, you could use it in the following sentence: "John and his gang decided to plan a robbery to get enough money to pay off their debts."
Four criminals planning a robbery hole up in an old lady's house, deciding to kill her when she discovers their secret.
Snarled though her personal life was, Ms. Astin told a compelling tale: Her husband had planned a robbery, and he came home shaking and nearly in tears on the day the rabbi was shot.
Two cheerful stoners, planning a robbery to pay off a debt, get involved with violent dwarfs, satanists, a millionaire hippie in a coma, a junkie prostitute who appears to be dead and a Russian drug baron and his henchman.
The two men are believed to have been planning a robbery of a social club near West 154th Street when the captain, Kenneth Girven, drove past and saw one of them duck behind a vehicle.
Dominik moves the story up a few decades, to the fall of 2008, but films the novel's plot virtually scene for scene: opening with three guys — an older "idea" man and two young hoods — planning a robbery of a mob-backed card game, then following the two toughs as they knock over the game in the bowels of a seedy motel.
Six years, and thousands of interviews, later, he finished a painstakingly-detailed, utterly dispassionate account of the murders by two small-time crooks, who planned a robbery with no witnesses, and ended up with four corpses and a little over forty dollars in cash.
Nor does Google actively or passively (through automated means) scan users' email accounts for other types of criminal activity, like planning a robbery, for example.
Clearly planning a robbery.
"All it suggested to me was three simple minded hoods planning a robbery," Tony Mastroianni wrote in the Cleveland Press.
On December 6 , 1995 three members of a gang now known as the Essex Boys were lured to a deserted farm track near Rettendon, England on the pretense of planning a robbery.
