Errand boy has to hire a family (9)
I believe the answer is:
parentage
'family' is the definition.
(I've seen this before)
'errand boy has to hire a' is the wordplay.
'errand boy' becomes 'page' (page is a kind of errand boy).
'has' means one lot of letters goes inside another.
'to hire' becomes 'rent' ('rent' can be a synonym of 'hire').
'rent'+'a'='renta'
'page' enclosing 'renta' is 'PARENTAGE'.
(Other definitions for parentage that I've seen before include "Who's your father (and mother)?" , "Family origins" , "results from birth" , "child-minders" , "Ancestors" .)