Cause of some wildfires (5)

I believe the answer is:
arson
(Other definitions for arson that I've seen before include "serious offence" , "Sonar (anag.)" , "Act of a pyromaniac" , "Fire requiring forensic study" , "Be pettish" .)
I believe the answer is:
arson
(Other definitions for arson that I've seen before include "serious offence" , "Sonar (anag.)" , "Act of a pyromaniac" , "Fire requiring forensic study" , "Be pettish" .)