Children's game is pretty devoid of content (1-3)
I believe the answer is:
i-spy
'children's game' is the definition.
(I Spy is a guessing game)
'is pretty devoid of content' is the wordplay.
'devoid of content' means to remove the middle letters (the content of the word is emptied out).
'pretty' with its centre removed is 'py'.
'is'+'py'='I-SPY'
(Other definitions for i-spy that I've seen before include "Wordgame" , "Game played with young children" , "Child's game: ''. ... with my little eye'" , "Children's alphabet game" , "Children's guessing game" .)