Chief raised part of ransom in Oregon (8)
I believe the answer is:
geronimo
'chief' is the definition.
(I know that Geronimo is a Indian chief)
'raised part of ransom in oregon' is the wordplay.
'raised' is a reversal indicator (going up in a down clue).
'part of' says the answer is hidden in the clue.
'ominoreg' can be found hidden inside 'ransom in oregon'.
'ominoreg' in reverse letter order is 'GERONIMO'.
(Other definitions for geronimo that I've seen before include "Cry of exhilaration" , "Whee!; Apache chief" , "battle cry" , "Brave leader" , "Famous Apache chieftain" .)