What domestic arsonist may do? One gives a warning (10)
I believe the answer is:
lighthouse
'one gives a warning' is the definition.
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for lighthouse that I've seen before include "it sends a warning" , "It was a wonder" , "Beamer" , "Warning feature for shipping" , "tower" .)