Alli has struck 17 goals for Spurs this season as his burgeoning profile in English football continues to grow, with manager Mauricio Pochettino describing him as "one of the best young players in the world".
Already he has been linked with a move to Zinedine Zidane's side that would see him following in the footsteps of former Spurs stars Luka Modric and Gareth Bale and making a switch to the Santiago Bernabeu, with former Los Blancos star Michel Salgado eager for his old club to pursue the 20-year-old.
Swansea welcome Spurs to the Liberty Stadium on Wednesday night. Ahead of kick-off, Clement, who served as Carlo Ancelotti's assistant manager at the Santiago Bernabeu between 2013 and 2015, was quizzed on the possibility of the England international making the move.
He told reporters: "Why can't he make the step up? He's still so young. All the best players get linked with Real Madrid, Eden Hazard is another one who is being linked at the moment," the Daily Express reports. "But if these teams want to do well and challenge for trophies, they've got to try and keep their best players.
"Like any player, the more consistent you are, and you're challenging at the top, then you're going to be of interest to arguably bigger clubs."
Swansea welcome Spurs to south Wales sat just a point above the relegation zone following their goalless draw with Middlesbrough on Sunday. Top scorer Fernando Llorente missed that game due to an ankle injury but Clement has slim hopes of the Spaniard returning on Wednesday for the visit of Pochettino's side.
Tottenham, meanwhile, could be without midfielder Victor Wanyama, with Harry Kane and Danny Rose still unavailable due to respective ankle and knee injuries.