Check car temperature (5)
I believe the answer is:
audit
'check' is the definition.
(an audit is an examination or check)
'car temperature' is the wordplay.
'car' becomes 'audi' (Audi is a German car brand).
'temperature' becomes 't' (abbreviation).
'audi'+'t'='AUDIT'
(Other definitions for audit that I've seen before include "Check of books" , "Financial investigation" , "assessment" , "Stocktake" , "Conduct annual check of firm's accounts" .)