Official publicity cars pursued by turncoat, we hear (13)
I believe the answer is:
administrator
'official' is the definition.
(thesaurus)
'publicity cars pursued by turncoat we hear' is the wordplay.
'publicity' becomes 'ad' (short for advert).
'cars' becomes 'minis' (Mini Coopers).
'pursued by' means one lot of letters go next to another.
'turncoat' becomes 'traitor' (I've seen this in another clue).
'we hear' shows a homophone (sound like).
'traitor' sounds like 'trator'.
'ad'+'minis'+'trator'='ADMINISTRATOR'
(Other definitions for administrator that I've seen before include "Business organiser" , "One who manages or directs" , "One who manages an organisation" , "One managing business affairs" , "Manager, controller" .)