The youngster got his first goal for the club but was also sent off in a 3-2 defeat to Galatasaray.
While Spurs are still in a good position in the Europa League group stages, Davies admits he had to console Lankshear post-game.
"Probably a little bit too late," he said when asked about the second-half fightback.
"Unfortunately for Will it is tough and these things happen but he'll learn from that. Look, he's pretty devastated in there but it's up to us to help him through it now. It was a valiant fight in the end but not quite enough."
He added: "He's gutted in there, he feels like he's probably let the team down. It's just part and parcel of football.
“Every game is different, every circumstance is different and tonight when he went off we went down to ten men and we had to work hard. It's one of those things. The game is done now and he will learn from that for sure."