The question of dock control in red clover and grass leys has come up before but the consensus is even Clovermax will kill the clover before it kills established docks
I used 24db with an amidosulfuron type product years ago. It didn’t kill the red clover but was like a pause button on growth until it was cut. Didn’t really kill the docks either but was better than nothing at the time.
Correction: I think it was pinnacle in the mix.