Basic arsenal includes vehicles (4)
I believe the answer is:
cars
'vehicles' is the definition.
(car is a kind of vehicle)
'basic arsenal includes' is the wordplay.
'includes' indicates the answer is hidden within the clue.
'CARS' is hidden in the letters of 'basic arsenal'.
(Other definitions for cars that I've seen before include "... when these may be driven?" , "Automobiles" , "Motor vehicles" , "Private vehicles" .)