Does "set up...sting" mean "set up... a trap"?

Yes a 'sting' is a trap. The essential feature of a sting which distinguishes it from other types of trap is that a sting operation is deceptive. Stings may be carried out both by criminals and law-enforcement agencies.

Examples:

Deploying a 'bait' car to catch automobile thieves
Police officer pretending to be a drug user to catch drug dealers
Police officer pretending to be a hit man to prevent a murder.

A famous police sting took place in the USA where a police department wrote letters to a large number of people who were wanted for e.g. unpaid fines. The letters pretended to be from a lottery and announced that the named person had won a prize which could be collected from a warehouse. When the wanted criminals arrived they were arrested. A large number of people were fooled.

However, the term was coined by confidence tricksters to describe a trap to ensnare the unwary who thought they'd swindle someone, but who were in their turn swindled.

Excellent.
Thank you both.

I once set up a sort-of sting to get rid of the 6 nasty caretakers/security staff in our big apartment block who nobody liked.
I pretended to have a friendly chat with them but secretly tape-recorded the conversation on a hidden recorder. They said some very self-incriminating things and after I sent the tape to their bosses, all 6 were fired..

Here's a great scene from the classic movie "The Sting"



Orister, the stepup is that at the start of the clip, the man named Lonagan tells his henchman to "fix the deck" (of cards) so that he'll get 9 nines, and Paul Newman (a con man) will get 3's.

A lot of betting back and forth, for a lot of money. You can clearly see Paul Newman holds 3's and Lonagan holds 9's.

But when they have to show their hands, Newman shows he had Jacks (that wins over 9's)

Lonagan has been stung. He thought he was going to con Newman, but in return he got conned (stung).

BTW, I don't know if anyone noticed, but those are AA poker chips they're using, the symbol with the circle with a triangle in it. They give them out in various colors to newcomers, and people w/ various times of sobriety.

Maybe they were using them so that if they were busted for an illegal poker game, they could claim they were just having an AA meeting.