Enraged criminal intercepted by motorway officer (8)
I believe the answer is:
gendarme
'officer' is the definition.
(gendarme is a kind of officer)
'enraged criminal intercepted by motorway' is the wordplay.
'criminal' indicates an anagram.
'intercepted by' means one lot of letters goes inside another (I've seen this in other clues).
'motorway' becomes 'M' (as in motorway names - M1, M4 etc).
'enraged' with letters rearranged gives 'gendare'.
'gendare' going around 'm' is 'GENDARME'.
(Other definitions for gendarme that I've seen before include "An arresting Frenchman?" , "continental copper" , "policeman in Paris?" , "see in Paris!" , "Member of the French police" .)