Native American chief upset about reactionary slogan used by Trump (8)
I believe the answer is:
sagamore
'native american chief' is the definition.
'sagamore' can be an answer for 'chief' (I've seen this before). I'm not sure about the 'native american' bit.
'upset about reactionary slogan used by trump' is the wordplay.
I cannot really understand how this works, but
'about' could be 're' ('re' means regarding or about) and 're' is found within the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Another definition for sagamore that I've seen is " N American Indian chief".)