It is obvious the French go in the vehicle (5)
I believe the answer is:
clear
'it is obvious' is the definition.
(similar in meaning)
'the french go in the vehicle' is the wordplay.
'the french' becomes 'le' ('the' in French).
'go in' indicates putting letters inside.
'the vehicle' becomes 'car' (car is a kind of vehicle).
'le' going inside 'car' is 'CLEAR'.
(Other definitions for clear that I've seen before include "Easily understood" , "Exculpate" , "Pellucid" , "Bold" , "Plain; unblock" .)