Former Racing 92 player Lavanini, 26, joins from Argentine side Jaguares and has 47 caps for the Pumas.

"It is an exciting challenge for me to make the move to the Premiership next season," he told the club website.

Leatigaga, 25, most recently played for French side Biarritz and has also had a spell with Piacenza in Italy.

The front rower won the last of his five Samoa caps in July 2017.

"Tigers has a big history of producing some of the game's best front-rowers and have a big focus on that part of the game," he said.

Hooker Clare, 27, has played for Northampton and Bedford since leaving Welford Road.

He said: "Geordan [Murphy, head coach] has such a passion for the club and I want to be a part of what he's building at the club."