### Clue: Indication of agreement to accept mail when services are abandoned because of this? (8)
### Answer: APOSTASY 
 ### Explanation: Definition: services are abandoned because of this
 AY(an indication of agreement;yes) **containing**(to accept) [ POST(the mail;correspondence) + AS(at the same time;when, as in "as/when dawn breaks…") ].
Answer: The "this" in the defn. A departure from;abandonment of one's religion, including religious services, of course.