Mediums
I believe the answer is:
psychics
'mediums' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for psychics that I've seen before include "They claim the ability to see the future" , "Spiritualists or mediums" , "People who claim to be able to contact the dead" , "They claim to be in touch with the spirit world" , "They claim to have occult powers of communication with the dead" .)