A job accompanying the French missionary (7)
I believe the answer is:
apostle
'missionary' is the definition.
(thesaurus)
'a job accompanying the french' is the wordplay.
'job' becomes 'post' (post is a kind of job).
'accompanying' means one lot of letters go next to another.
'the french' becomes 'le'.
'a'+'post'+'le'='APOSTLE'
(Other definitions for apostle that I've seen before include "Ardent espouser of new system" , "Augustine, say" , "Evangelist, proponent" , "James, perhaps" , "Burgess originally" .)