Rosseti

I don't know of any rewards for a clan like that.

so what is it for? because I was in 1st place with more than 1000 wins in front of the 2nd place.. for nothing? hard to keep playing...

I believe that the win count is purely for personal pride and friendly competition.
Clan points are for pride too. Maybe that will give rewards after a while, but battle wins is just a case of putting time in. Increasing that number isn't hard by itself, so I don't expect it to give rewards.