Hairstyle upset some poor father (4)
I believe the answer is:
afro
'hairstyle' is the definition.
(type of hairstyle)
'upset some poor father' is the wordplay.
'upset' says the letters should be written backwards.
'some' says the answer is hidden in the clue (some of the parts of the word are used).
'orfa' is hidden within 'poor father'.
'orfa' backwards is 'AFRO'.
(Other definitions for afro that I've seen before include "Hair-style from Dark Continent" , "Big hair?" , "Hairstyle adopted by the young Michael Jackson" , "Rounded, curled hairstyle" , "Style of haircut" .)