2545: With a twist - solution
Suggested by 41, the other unclued lights were worms entered backwards in the grid. To comply with the preamble, 6 down needs to be CESTODE (the individual worm) rather than CESTODA (the subclass). First prize Leslie Verth, Newton Mearns, Glasgow Runners-up Roslyn Shapland, Ilkeston, Derbyshire. Oenone Green, Feltham, Middlesex