Clue: Dashed good work everyone put in on education (8)
Answer: GALLOPED
Explanation: Definition: Dashed
 [ G(abbrev. for "good") + [OP(abbrev. for "opus", a major piece of literary or musical work) ] **containing**(… put in) ALL(everyone) **placed above**(on, in a down clue) ED(abbrev. for "education").