Second sight (3)
I believe the answer is:
esp
'second sight' is the definition.
(extrasensory perception)
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" , "Initially, clairvoyance or telepathy" , "Second sight (abbr)" , "Extrasensory perception (abbrev.)" , "Apparent power to perceive things that others can't, in short" .)