Ok. I've been doing this puzzle for the best part of the whole day (save a break to bake a cake) and I'm utterly stuck on the last three.
27ac Take turns to restrict entrance (9)
I have: S-T-L---D
20dn Dog's foot a state — iodine applied (7)
I have: C-S----
25ac Agreed to drop odds, when they're lined up (8)
I have: E-S---E-
I have counted 11 of the 12 themed requirements, so only one of the clues (I think) requires the theme.
All help much appreciated.