Father's upset, hurt by Red Indian (6)
I believe the answer is:
apache
'red indian' is the definition.
'apache' can be an answer for 'indian' (Apache is an example). I'm not sure about the 'red' bit.
'father's upset hurt by' is the wordplay.
'father' becomes 'pa' (pa can mean dad or father).
'upset' is a reversal indicator.
'hurt' becomes 'ache' (synonyms).
'by' says to put letters next to each other.
'pa' back-to-front is 'ap'.
'ap'+'ache'='APACHE'
Can you help me to learn more?
(Other definitions for apache that I've seen before include "American Indian - French gangster" , "Fierce Indian of American SW, or Paris ruffian" , "Geronimo was one" , "ruffian in capital of France" , "American Indian of New Mexico and Arizona" .)