Six vehicles for clergymen (6)
I believe the answer is:
vicars
'clergymen' is the definition.
(vicar is a kind of clergyman)
'six vehicles' is the wordplay.
'six' becomes 'VI' (Roman numerals).
'vehicles' becomes 'cars' (car is a kind of vehicle).
'vi'+'cars'='VICARS'
'for' is the link.
(Other definitions for vicars that I've seen before include "those taking tarts to party" , "clergymen" , "Members of clergy in charge of churches" , "Ministers" .)