### Clue: East Anglian town that's 'stumped' (stumped in time of prosperity) (6)
### Answer: BOSTON 
 ### Explanation: Definition: East Anglian town that's 'stumped'
 ST(abbrev. for "stumped" by the wicket-keeper, in cricket scores) **contained in**(in) BOON(an advantage/something that is beneficial – isn't that rather different from "boom"/a period of great economic growth/a time of prosperity?).
Defn: …, ie. has a parish church, St. Botolph's, nicknamed the Boston Stump.