Falls in a river over to the west (7)
I believe the answer is:
niagara
'falls' is the definition.
(Niagara Falls)
'a river over to the west' is the wordplay.
'river' becomes 'r' (abbreviation for river).
'over' becomes 'again' (I've seen this in another clue).
'to the west' says the letters should be written backwards (letters written right to left or 'east to west').
'a'+'r'+'again'='aragain'
'aragain' in reverse letter order is 'NIAGARA'.
'in' is the link.
(Other definitions for niagara that I've seen before include "1953 Marilyn Monroe film noir thriller" , "Great waterfalls on Canadian-US border" , "North American waterfall" , "N American river and Falls" , "It falls in North America" .)