Customs clearance is the fulfillment of necessary formalities and procedures arising in connection with the movement of goods and vehicles across the customs border.
If you are engaged in the export or import of goods, then you regularly have to deal with customs. After all, in accordance with the legislation, all goods that cross the border of Russia must pass customs clearance. This is necessary in order for the state to be able to control foreign economic activity.
Everyone who has ever carried out customs clearance knows how difficult this procedure is. 
It requires care, knowledge of the legal framework and a lot of time.