Mind games involving heartless schoolboy and child (6)
I believe the answer is:
psyche
'mind' is the definition.
('psyche' can be a synonym of 'mind')
'games involving heartless schoolboy and child' is the wordplay.
'games' becomes 'pe' (abbreviation for Physical Education).
'involving' indicates putting letters inside.
'heartless' says to hollow out the word (remove centre letters).
'and' is a charade indicator (letters next to each other).
'child' becomes 'ch'.
'schoolboy' with its middle taken out is 'sy'.
'sy'+'ch'='sych'
'pe' going around 'sych' is 'PSYCHE'.
(Other definitions for psyche that I've seen before include "Inner self" , "The soul, spirit or mind" , "Innermost self" , "Individuality" , "Wife of Cupid" .)