### Clue: Hero receives shocking treatment following extra event to fill unexpected vacancy (2-8)
### Answer: BY-ELECTION 
 ### Explanation: Definition: event to fill unexpected vacancy
 [ LION(figuratively, a hero who would be lionised) **containing**(receives) ECT(abbrev. for "electroconvulsive therapy";electric shock treatment for severe mental disorders) ] **placed after**(following) BYE(in cricket, a run scored from a ball not struck by a batsman, and awarded as an extra to the team).
Answer: An election to find a replacement for a seat in Parliament vacated by the incumbent before the end of the normal term of office.