Mind game for children? (7)
I believe the answer is:
marbles
This clue is a double definition.
'mind' is the first definition.
(I've seen this before)
'game for children?' is the second definition.
(Other definitions for marbles that I've seen before include "Small spheres of glass - statuary" , "Small balls of coloured glass" , "Sculptures" , "Mind" , "You'll be mad if you lose them" .)