Moving ___
'moving' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for astir that I've seen before include "abroad" , "Awake and out of bed" , "Out of bed or on the move" , "Up and about -- is art (anag)" , "Excitedly moving" .)
(Other definitions for van that I've seen before include "Forefront, vehicle" , "Leading point of army" , "Commercial vehicle or front of army" , "camper?" , "Army front or business vehicle" .)