Clethodim will kill grasses and will not harm clover or radish.
There is no herbicide that will kill broadleaf weeds in a mix of clover and brassicas. They will either kill the clover or kill the brassicas or both.
If the weeds are really bad such that the whole plot is at risk of getting choked out, I’d be tempted to forget the radish and try to save the clover. There are clover-safe broadleaf weed killers, the most common is 2-4-DB. Note that this is NOT the same as 2-4-D. The B at the end is significant. But again, this herbicide will kill the radish.
This is the reason I don’t like mixing anything with clover except chicory. If clover is kept pure, then you have weed control options. Once you start blending broadleaf plot crops into clover, weed control gets difficult or impossible.
Grouse