Mean male offspring to become a clergyman (6)
I believe the answer is:
parson
'a clergyman' is the definition.
(parson is a kind of clergyman)
'mean male offspring' is the wordplay.
'mean' becomes 'par' (I've seen this before).
'male offspring' becomes 'son' (son is a kind of male offspring).
'par'+'son'='PARSON'
'to become' acts as a link.
(Other definitions for parson that I've seen before include "Rector; clergyman" , "Aprons (anag.)" , "A rector or vicar" , "One with benefice" , "service provider" .)