Examine car before start of trip (5)
I believe the answer is:
audit
'examine' is the definition.
(auditing is a kind of examining)
'car before start of trip' is the wordplay.
'car' becomes 'audi' (audi is a german car brand).
'before' says to put letters next to each other.
'start of' indicates taking the first letters.
The first letter of 'trip' is 't'.
'audi'+'t'='AUDIT'
(Other definitions for audit that I've seen before include "Financial inspection" , "Verify accounts" , "HMRC inspection" , "Official inspection of company accounts" , "Roman Aquae Sulis" .)