Penniless clergyman causing offence (5)
I believe the answer is:
arson
'offence' is the definition.
(crime of illegally starting a fire)
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for arson that I've seen before include "Incendiarism" , "Fire-raiser's crime" , "Pyromaniac crime" , "matchplay, say?" , "Crime of fire-setting (5)" .)