"The Texans picked up Jadeveon Clowney's fifth-year option recently, comfortably ahead of the May 2 deadline. The option will pay Clowney, the top overall pick in the 2014 NFL Draft, $13.846 million in 2018 and is guaranteed for injury upon exercise."
If it means his contract is guaranteed in spite of injury, look for him to have a major hangnail which forces him to miss the entire season.
Same article also mentioned that if they negotiate an extension with Clowney before they get one done with Nuk, it would probably make Nuk want to go in free agency. I think that needs to happen anyway. Him and Clownhead on the same team is just wrong. Of course, if Houston were to draft DW4, it would be worth hanging around.