### Clue: Mantra thought cynical provokes new high street riot police only at the end sent in (4,2,4,8)
### Answer: WE’RE IN THIS TOGETHER 
 ### Explanation: Definition: Mantra thought cynical
  **Anagram of**(provokes) [NEW HIGH STREE RIOT **plus**(sent in) E{last letter of(only at the end) "police"}]. 
Answer:  Slogan,mantra first mentioned by current British PM at the Conservative Party Conference in 2010, and subsequently often repeated, but cynically thought of, as actions don't quite fit, so I gather.  "We're (all) in this together" also reminds one of "Misery loves company". 🙂