Anti-Diversion Clause
  
International trading involves a lot of red tape, things like tariffs, regulations about what is allowed and what isn't and rules governing what kind of stuff can go where. An anti-diversion clause is part of this web of governmental regulation.
Specifically, it states where a particular export can go. The clause appears on the paperwork accompanying an export, asserting that it can't be diverted to a different location than its stated destination. This might come up in a circumstance where a particular product is subject to sanctions to certain countries, or is otherwise not allowed to travel to specific locations.
The clause states that the export in question must only go to its stated destination. Whether this happens or not might be a different story. What happens on a cargo ship stays on a cargo ship (ever seen The Wire, Season 2?). But legally, the export is only supposed to go to one place.