Middle bears once lighting fires (5)
I believe the answer is:
'lighting fires' is the definition.
Although both the answer and 'fires' are nouns, they are not in the same form of the noun. However, I know that 'fires' relates to this answer.
'middle bears once' is the wordplay.
'ARSON' is hidden in amongst the letters.
However, I am unsure how this is indicated.
Can you help me to learn more?
(Other definitions for arson that I've seen before include "It may get you in court" , "Pyromaniac's crime" , "criminal fire-raising" , "Crime involving fire" , "Incendiary act" .)