Last two: 17a - "Startled to find circle in radial diameter": s-o-k--. Must be "shocked" (?), but why?;
11d - "Died in the embrace of 3": -e---e. Possibly "beadle", with "d" in "beale", but again am struggling to work out why.
Thank you both: as usual, I found an answer which fitted the definition, and tried to get the rest of the clue to fit that. Some people (me) never learn.