The 26-year-old, who can play in a number of positions, was most recently with Grimsby Town, appearing 39 times in the 2020/21 season as the Mariners were relegated.
Now, Grimsby's loss is Mansfield's gain.
Clough said: “Even teams that go down have good players.
“If you can get one or two players from those teams, they are still good League Two players.”
“Elliott is a good player with good experience at this level. He is one that can cover several positions.
“He knows the league, knows a few positions, is a good age and has good experience, so it was a bit of a no-brainer for us.
“When we’re aiming for just 17 or 18 established outfield players, we need a few players who can move around the team.
“It’s very important to have those sort of players and Elliott falls into that category.
“He sees himself as a defender, but wherever he gets in the team, he will be one that is difficult to get out.”
Hewitt began his career with Macclesfield Town, graduating from the club’s youth academy, before sealing a move to Ipswich Town in 2012.
The defender spent three years with the Blues, a stint that included loan spells with Gillingham and Colchester United, while also making 14 outings in the Championship.
In 2015, Hewitt made a permanent switch to Notts County making over 130 league appearances for the Magpies in a four-year period.
He spent the last two seasons at Blundell Park, appearing over 60 times for the Mariners.