Agent following current game (1-3)
I believe the answer is:
i-spy
'game' is the definition.
'agent following current' is the subsidiary indication.
'agent' becomes 'spy' (spy is a kind of agent).
'following' is a charade indicator (letters next to each other).
'current' becomes 'i' (symbol for electric current).
'spy' after 'i' is 'ispy'.
(Other definitions for i-spy that I've seen before include "Game played with young children" , "Children's guessing game" , ". ... with my little eye (children's game)" , "Children's alphabet game" , "Children's observational game" .)