The usual offspring of a clergyman (6)
I believe the answer is:
parson
'a clergyman' is the definition.
(parson is a kind of clergyman)
'the usual offspring' is the wordplay.
'the usual' becomes 'par'.
'offspring' becomes 'son' (son is a kind of offspring).
'par'+'son'='PARSON'
'of' is the link.
(Other definitions for parson that I've seen before include "Churchman" , "Anglican clergyman" , "One with benefice" , "A rector or vicar" , "Aprons (anag.)" .)