he 25-year-old, outstanding in a holding role in the stunning weekend win over champions Leicester City, is now contracted at the KCOM Stadium until the summer of 2019.
Clucas enjoyed a breakthrough 2015-16 campaign with the Tigers after joining from Chesterfield in July 2015 and contributed six goals and eight assists in 52 appearances in all competitions.
On penning a new deal, Lincoln-born Clucas said: “I am delighted to extend my stay with the club.
“I had a wonderful first season here, which culminated in the club winning promotion to the Premier League. It was a thoroughly enjoyable campaign and one that will stay with me for a long, long time.
“I have got a great connection with the staff, players and fans here. It is a fantastic group to be part of.
“The spirit in the squad is second-to-none and we are determined to achieve our goals in the Premier League this season.”
Caretaker manager Mike Phelan added: “Sam was an important part of our success last season, with his creativity and ability to score goals from midfield.
“However, it is not just his ability that makes him a key part of the squad, but also his commitment, determination and focus.
“I am confident that he will continue to flourish in the top-flight of English football after his impressive performance against Leicester on Saturday and be a central component of the squad not only this season, but in the years to come.”