Six to transport cleric (5)
I believe the answer is:
vicar
'cleric' is the definition.
(I know that vicar is a type of Priest)
'six to transport' is the wordplay.
'six' becomes 'VI' (Roman numerals).
'to transport' becomes 'car' (car is a method of transport).
'vi'+'car'='VICAR'
(Other definitions for vicar that I've seen before include "Oliver Goldsmith wrote 'The . . . . . of Wakefield'" , "Cleric" , "Goldsmith novel ''The . . . . . of Wakefield'' (5)" , "Man (or woman) of the cloth" , "Parish priest" .)