"Let through" means to allow something or someone to pass or be transmitted. There are several synonyms for this phrase. "Clear" can be used in the context of a path or a route being cleared for someone to pass through. "Allow" is another synonym, which means to permit or give permission for something to happen. "Permit" is another similar word meaning to allow. "Admit" is a synonym which also means to allow entry or passage. "Enable" can be used to describe creating conditions that allow something to happen or giving someone the ability to do something. "Facilitate" means to make it easier for something to occur. "Pass" is another synonymous word that indicates allowing someone or something to go through a path.