Game is pretty empty
I believe the answer is:
i-spy
'game' is the definition.
'is pretty empty' is the subsidiary indication.
'empty' means to remove the middle letters.
'pretty' with its middle removed is 'py'.
'is'+'py'='ispy'
(Other definitions for i-spy that I've seen before include "Child's game: ''. ... with my little eye'" , "Children's alphabet game" , "Children's guessing game" , "Game played with young children" , ". ... with my little eye (children's game)" .)