Strong woman in river (6)
I believe the answer is:
amazon
I believe this clue is a double definition.
'strong woman' is the first definition.
(I've seen this before)
'river' is the second definition.
(Amazon is an example)
'in' is the link.
(Other definitions for amazon that I've seen before include "Mythic woman warrior" , "Encourage, ask" , "Mighty river of S America, or tough woman" , "S. America's longest river" , "Mythical woman warrior and river" .)