Even if that release clause is true, it only activates in the summer of 2019. So, Spurs can easily say no to any transfer until then, or ask for £50m+ this summer. Either way, he's injured, so it's strange that him not being in the squad against Juve means he's going to leave in the summer, especially given that he wasn't in the squad against Arsenal a few days back either. He clearly hasn't fully recovered from injury, and imo it's just another attempt by Matt Law to destabilise another one of Chelsea's rivals.