Improve motoring event (5)
I believe the answer is:
rally
I believe this clue is a double definition.
'improve' is the first definition.
(thesaurus)
'motoring event' is the second definition.
(I've seen this before)
(Other definitions for rally that I've seen before include "Mass meeting; car race" , "Recover strength after illness" , "motoring event" , "Assemble - recover" , "Call to arms - series of strokes" .)