Empty vehicle seen round outskirts of Lille (5)
I believe the answer is:
clear
'empty' is the definition.
(I've seen this before)
'vehicle seen round outskirts of lille' is the wordplay.
'vehicle' becomes 'car' (car is a kind of vehicle).
'seen round' indicates putting letters inside.
'outskirts of' means to remove the middle letters (only letters on the outskirts).
'lille' with its middle removed is 'le'.
'car' enclosing 'le' is 'CLEAR'.
(Other definitions for clear that I've seen before include "Bold" , "bound over" , "Comprehensible" , "Plain; unblock" , "Transparent, easy to see through" .)