Row northwards, river dwellers -- but river goes west (3-2)
I believe the answer is:
set to
'row' is the definition.
(I've seen this before)
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for set to that I've seen before include "Fight, argument" , "Row" , "Altercation" , "Spat" , "Get cracking; start fighting" .)