Here is the full list of all 16 Clandestinity of Elsie achievements.
You finally found Elsie.
Return to Burnie's Garage.
Kill an Alchy.
Enter the sewers (again).
Kill a Thorn.
Leave the sewage plant.
Diverted the water flow.
Escape the Singed ambush.
Gather medical supplies at the hospital.
Find the Blood Bag at the Troy Restaurant.
Find the pendant.
Kill 10 Singed.
Activate the elevator at the Yorkshire Apartments.
Kill a Victim.
Save your game for the first time.
Went to the Cunningham home.