Man being prepared runs vehicle inside (7)
I believe the answer is:
servant
'man' is the definition.
(thesaurus)
'prepared runs vehicle inside' is the wordplay.
'prepared' becomes 'set' (I've seen this before).
'runs' becomes 'r' (cricket abbreviation).
'vehicle' becomes 'van' (van is a kind of vehicle).
'inside' indicates putting letters inside.
'r'+'van'='rvan'
'set' enclosing 'rvan' is 'SERVANT'.
'being' acts as a link.
(Other definitions for servant that I've seen before include "Eg, a footman or maid" , "Perhaps chauffeur" , "Butler, e.g." , "One working for another" , "Domestic worker" .)