Very nice out-of-the box thinking Paddy. Almost works – especially the wordplay. It does miss out on the deceptive use of “Can” for “Tin” by the setter but the main reason it doesn’t work is that “Calanthe” can’t be defined as “medicine”. At best, the definition would have to say “medicinal plant” or something like that. In the grid itself, crossing letters would’ve helped to avoid any confusion.