Our child mentioned deliberately setting fire to property (5)
I believe the answer is:
arson
'mentioned deliberately setting fire to property' is the definition.
I know that 'fire' relates to this answer.
'our child' is the wordplay.
'our' becomes 'ar' (I am not sure about this - if you are sure you should believe this answer much more).
'child' becomes 'son' (male child).
'ar'+'son'='ARSON'
Can you help me to learn more?
(Other definitions for arson that I've seen before include "Roans (anag)" , "Malicious fire-raising" , "matchplay, say?" , "Pyromaniac's crime" , "Malicious burning to destroy property" .)