### Clue: Falls head over heels once more with artist (7)
### Answer: NIAGARA 
 ### Explanation: Reversal(*head over heels*, for a Down clue) of AGAIN(*once more*) + RA(one from the Royal Academy, crosswordese for *artist*).  Defn:  That natural landmark shared by Canada and the USA.  Nice misdirection with "*Falls head over heels*".