Clergyman beginning to prevent crime (6)
I believe the answer is:
parson
'clergyman' is the definition.
(I know that parson is a type of clergyman)
'beginning to prevent crime' is the wordplay.
'beginning to' says to take the initial letters.
'crime' becomes 'arson' (crime of illegally starting a fire).
The first letter of 'prevent' is 'p'.
'p'+'arson'='PARSON'
(Other definitions for parson that I've seen before include "Churchman" , "service provider" , "One with benefice" , "Aprons (anag.)" , "A rector or vicar" .)