Brooke Guest struck 85, but Derbyshire fell to a three-wicket defeat to Kent in the Metro Bank One-Day Cup fixture at The County Ground.
Kent were sliding to defeat at 106 for 6 chasing 207 with Samit Patel taking 3 for 30 but Leaning and Grant Stewart’s 48 from 39 balls revived them.
Leaning and Matt Parkinson then added 33 from 43 balls to see Kent over the line with 28 balls to spare at 207 for 7.
Brooke Guest made 85 from 117 balls, sharing an eighth wicket stand of 75 with Harry Moore who made a career-best 40 to take Derbyshire to 206 with Parkinson claiming 3 for 23.
Kent bowled well on a used pitch with George Garrett finding late movement to have Harry Came caught behind.
But there were some soft dismissals starting with Luis Reece who was run out by a direct hit from cover in the seventh over.
David Lloyd drove back a low return catch to Grant Stewart but it was Parkinson’s spell which put Derbyshire on the back foot.
Guest and Anuj Dal ran well, picking up quick singles and twos, but Parkinson tempted Dal into a big drive which landed in the hands of long on.
Patel pulled Jas Singh for the only six of the innings but Parkinson snared him in the 25th over with a slower ball which he drove to cover.
When Yousaf Bin Naeem was trapped lbw half forward, Derbyshire were 109 for 6 with Guest’s 77 ball 50 holding his side together.
Garrett returned to bowl Zak Chappell with a late inswinger but Moore provided Guest with the support he deserved to give the hosts respectability.
The pair kept the board ticking over without taking risks before Moore ramped and cut Jas Singh for three consecutive fours in the 44th over.
Guest’s excellent innings ended when he pulled Charlie Stobo to mid-wicket and Moore went in the 47th over, run out at the non-striker’s end by a direct hit from cover.
But they had given the bowlers something to defend and Moore struck when Marcus O’Riordan was caught behind down the leg side.
Moore saw Joey Evison dropped at first slip before Leaning dispatched him for four boundaries in his next over.
Derbyshire needed inspiration and Daryn Dupavillon provided it by taking a stunning one handed diving catch at mid on off Patel to remove Evison for 32.
Patel struck again in his next over when Jaydn Denly was cramped for room trying to pull and holed out to long on leaving Kent 78 for 3.
Derbyshire sensed there was an opening when Harry Finch played a loose drive at Pat Brown and this time David Lloyd made no mistake at slip.
The pressure was now on Kent who started to unravel as two more wickets went down in four overs.
Ekansh Singh clipped Chappell to mid-wicket and Stobo got a leading edge to slip trying to work Patel through the leg side
But Leaning gave Kent hope, reaching 50 from 79 balls and with Stewart, he steered his side back into the contest.
Stewart pulled Brown for two sixes and appeared to be winning the game until he lifted Chappell to fine leg where Moore managed to take a superb catch without carrying the ball over the rope.
But Leaning hit Moore for three fours and with Parkinson saw his team to a win that keeps their slender hopes of making the knock-out stages alive and dents Derbyshire’s chances of qualifying.