Work for each group of schoolchildren (7)
I believe the answer is:
perform
'work' is the definition.
(thesaurus)
'each group of schoolchildren' is the wordplay.
'each' becomes 'per' ('per' can mean for each).
'group of schoolchildren' becomes 'form' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'per'+'form'='PERFORM'
'for' acts as a link.
Can you help me to learn more?
(Other definitions for perform that I've seen before include "Carry out; act" , "Carry out (duties)" , "Act in play or film" , "seen to make a profit?" , "Act or execute" .)