Neil Chitty turned in the all-round display of the day to put Arundel in the top four.
Slow left-armer Chitty tooK 5-50 as Roffey, having chosen to bat first on a damp wicket, were all out for 145.
The hosts then tumbled to 3-3 before Chitty's 57 helped them win by two wickets in a tense finale.
He admitted: "Findon are favourites to win the league but the home straight can be the hardest bit so it could still be an exciting finish."
Findon have a handy 36-point advantage, though they had to work for their success at Henfield after Simon Helm's 75 guided the hosts to 198-6.
John Rogers led the reply with an undefeated 117 and the leaders got in with four wickets to spare, despite a haul of 5-88 from Rob Slaughter.
Steve Collins' 54 saw second-placed Goring to a six-wicket win at Clymping after the hosts posted 142-6.
Crawley's title bid hit the buffers at Burgess Hill as the home side's last pair held out for a draw.
Kevin Toulson was 76 not out in Crawley's 206-9, with Peter Billinghay bagging 5-53, but Hill held out on 134-9, Robert Hansford leading the resistance with 50.
The bottom three are showing few signs of staging a revival.
Pagham made just 102 in a six-wicket reverse at Barns Green, who were seen home by Roger Southgate's unbeaten 44.
East Preston were without a game while Petworth Park were skittled for 77 by Lindfield's Alex de Mierre, who finished with 7-29.
Graham Page had earlier made 53 of Lindfield's 168 all out, with Matthew Roberts taking 6-36.
The day's other game saw Ifield score 196-7 in a 56-run defeat of visitors Cuckfield. Graham Dean led the charge with 65.
In division two, Southwick's lead over Broadwater is up to 28 points after seamer Steve Martin took 5-19 to see off Pulborough.
Ansty also remain very much in the hunt thanks to a blast of 4-7 from Shaun Janman to skittle ten-man Wisborough Green for just 56.
Ansty meet Broad-water on Saturday while Southwick will look for big points against Broadbridge Heath.
Comments: Our rules
We want our comments to be a lively and valuable part of our community - a place where readers can debate and engage with the most important local issues. The ability to comment on our stories is a privilege, not a right, however, and that privilege may be withdrawn if it is abused or misused.
Please report any comments that break our rules.
Read the rules hereComments are closed on this article