Force of Red River (5)
I believe the answer is:
drive
'force' is the definition.
(driving is a kind of forcing)
'of red river' is the wordplay.
'of' indicates a hidden word.
'DRIVE' is hidden in the letters of 'red river'.
(Other definitions for drive that I've seen before include "spin" , "Force into action, impel" , "Propel; outing" , "natural urge" , "Determination, ambition" .)