Altaf scored 91 not out as the reigning champions amassed 306-7 and followed up by taking 5-74 with his leg spin as Yeadon were bowled out for 208.
The 20-point haul from their emphatic win gives them a 22-point lead with three games to play. Their only serious rivals are second-placed Woodlands.
Cleckheaton lost their first two wickets for 19 but recovered through Altaf and opener Andy Gorrod (84) with useful support from Michael Nicholson (47) and John Wood (40).
Tariq Mehboob (53) tried to hold Yeadon’s innings together before a last-wicket stand of 65 between Altaf Mohammed (30no) and Muhammad Saeed (27) lifted the score beyond 200 and earning a fourth batting point.
This defeat leaves Yeadon facing almost certain relegation.
Woodlands gained 19 points from their 88-run home win over Bradford & Bingley.
Simon Mason (36) and Chris Brice (45) held their innings together as paceman Jack Hartley and spinner Noman Ali each took three wickets.
Woodlands were struggling at 148-7 before big-hitting Sarfraz Ahmed smashed 61 off only 27 balls, including five sixes and four fours.
He dominated an unbroken eighth-wicket stand of 73 with Scott Richardson which helped Woodlands to reach 221-7.
Bingley were never in the hunt after losing their first four wickets for 24. Top scorer Chris Thompson (31) and acting skipper David Clow (23) shared a fifth-wicket stand of 58, but their side were dismissed for 133.
Like Yeadon, Morley are facing relegation after their 21-run defeat to fellow strugglers East Bierley.
Morley must have been confident of winning after Bierley collapsed from 116-3 to 125 all out with off spinner David Nebard taking 4-31.
However, they missed a great chance of a vital victory when they were bowled out for 106 with spinner Luke Jarvis taking 5-29.
New Farnley inflicted a third successive defeat on Pudsey St Lawrence after bowling them out for 56, with skipper Mark Lawson taking 4-9 with his pace bowling to set up a 120-run win.
Pudsey Congs continued their revival by beating Lightcliffe by 24 runs. Off-spinner Josh Wheatley took 6-48 as Congs were restricted to 162-9 but they hit back by bowling out the visitors for 138, pace bowler James Pearson taking 5-41.