Children's guessing game (1-3)
I believe the answer is:
i-spy
'children's guessing game' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for i-spy that I've seen before include "Children's guessing game" , ". ... with my little eye (children's game)" , "Children's observational game" , "Wordgame" , "Children's alphabet game" .)