North American falls (7)
I believe the answer is:
niagara
'north american falls' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for niagara that I've seen before include "Great waterfalls on US-Canada border" , "North American waterfalls" , "Horseshoe, American and Bridal Veil Falls, collectively" , "it's quite a height" , "US/Canadian falls" .)