### Clue: Belonging to a teaching organis­ation is ghastly, to be brief (2,1,8)
### Answer: IN A NUTSHELL 
 ### Explanation: Definition: to be brief
IN A NUT'S HELL='in a NUT is hell'="Belonging to a teaching organisation is ghastly" 
the NUT was the National Union of Teachers, which merged into the National Education Union