Id checker? (3)
I believe the answer is:
ego
'id checker?' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for ego that I've seen before include "Conceit - the Latin "I"" , "Vowel to disappear, < say another" , "Self-confidence" , "One's sense of self-importance" , "One's self image" .)