Well and truly stuck! 12across: Device allowing motion in one direction only. I have RA??T?T and feel reasonably sure about those letters but none of my crossword solving things can find a word/definition for that. Thanks.
Ah...thanks. I've done crosswords for the last hour and I think my eyes have gone wonky. The intersecting word was BREATHE and I had it spelt BREAATH. Doh!!!