16.d racehorse trainers brightest light is no super nova (6,4)s---l-, s---
18.a such is ones taste in music ,for example Carmen excluded (6,2,3,4,)-i----, --, -h-, r---
ist one could be "stable star". Astar considered stable and not about to blow up which is wahat a super nova is doing. Rest of the clue is self explanatory.