Just got in. Pleased to see that 5ac has been resolved, though I think its a very poor clue. But I'm still none the wiser about 27ac. Gentle hint anyone?
I think ixion is right about a misspelling in 2dn. I hadn't noticed.
Just one final loose end. Is 5ac supposed to be a "paired" answer? I suppose it is, though it doesn't really mean much to me. By my reckoning, that makes 18 paired answers, not 17.