Defoe had to pay £3,000 to charity last season after he lost a wager with Wilshere that Tottenham would finish above their north London rivals for the first time since 1995.
The Spurs striker lost the bet after his team threw away a 10-point lead over the Gunners. This season they are seven points ahead with 10 games left.
"We all know what happened last season," said Defoe.
"At the time, when I did have the bet, I thought we would have finished higher than Arsenal and I still feel like that now.
"Jack's a cool guy, there's a little bit of banter and even though we beat them quite comfortably, I still think they're a good side. But I suppose if Jack wants a little bet, it's no problem with me.
"We've not just got a great team now but a great squad. The spirit is great, the lads are buzzing and it's just a great time to be here."