Offence of minister losing head? (5)
I believe the answer is:
Here is my best explanation:
'offence' is the definition.
(I've seen this before)
'minister losing head?' is the wordplay.
'minister' becomes 'parson' ('parson' can be a synonym of 'minister').
'losing head?' means to remove the first letter.
'parson' with its first letter taken away is 'ARSON'.
'of' is the link.