One checks German car's put to one side (7)
I believe the answer is:
auditor
'one checks' is the definition.
'german car's put to one side' is the wordplay.
'german car' becomes 'audi'.
'put' is a charade indicator (letters next to each other).
'one side' becomes 'r' (abbreviation for right).
'audi'+'to'+'r'='AUDITOR'
(Other definitions for auditor that I've seen before include "Accounts inspector" , "One qualified to check accounts" , "Business accountant" , "Listener; scrutineer" , "Worker in accounts" .)