Affected to have worked hard in school (7)
I believe the answer is:
studied
'affected' is the definition.
(thesaurus)
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for studied that I've seen before include "deliberate" , "Read" , "Considered, learnt about" , "Examined" , "Learnt by reading" .)