It's played mainly by American schoolchildren (6)
I believe the answer is:
hookey
'it's played mainly by american schoolchildren' is the definition.
I can't judge whether this defines the answer.
'it's' is the wordplay.
I cannot quite see how this works, but
'it' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is found within the answer.
The remaining letters 'hooky' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for hookey that I've seen before include "What truants play?" , "Play ___ (from school?)" .)