Clue: Accounts really starting to rise alarmingly — they need settling first! (7)
Answer: ARREARS
Explanation: Definition: they need settling first
**A**ccounts **R**earing + **REAR **("to rise alarmingly") + **S** *(cant' see that indicated?)* 
*Am I missing something? Has the ***S ***been indicated in the clue? See comment 1 for a possible parsing.