Paranormal letters (3)
I believe the answer is:
esp
'paranormal letters' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for esp that I've seen before include "Apparent power to perceive things that others can't, initially" , "Apparent power to perceive things that others can't, in short" , "Second sight (abbr)" , "Initially, clairvoyance or telepathy" , "Extrasensory perception (abbrev.)" .)