Spider-Man Web of Shadows

There will be a mission early in the game that will explain how to do sing-kicks efficiently. Just after this mission, Luke Cage will ask you to set up a meeting with the other gang boss. You'll actually need to travel to a marker to start it.

Once you activate this mission at the marker, a couple of guys will appear in the street, defeat them. This will cause a group of 7-8 enemies at the end of the street. This group should stay clustered enough to get this achievement easily.

If for some reason you don't get it on the first group, several more groups appear afterward giving you plenty of opportunities.

If you fail to get the achievement during this mission however, chances are you are out of luck without loading an earlier save or restarting. Theoretically, you could get it later on, but there just will not be any good opportunities for it.

At the beginning of Act 3 right at the Stark Towers there are an infinite number of "Zombie Symbiotes" (White & Black). They are slow and in large groups.

Stand in the middle of a large group and block (Right bumper). Once you have 5 around your (I had 8 around me just to make sure). Jump out and then swing kick (Right trigger + X) into them.