Rang indeed but disordered (8)
I believe the answer is:
deranged
'disordered' is the definition.
(deranging is a kind of disordering)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for deranged that I've seen before include "Mentally unbalanced" , "Disordered, mentally perhaps" , "Crazy" , "Gardened, being quite mad" , "totally without reason" .)