Extreme racist upset daughter initially (7)
I believe the answer is:
drastic
'extreme' is the definition.
(I've seen this before)
'racist upset daughter initially' is the wordplay.
'upset' is an anagram indicator.
'daughter' becomes 'd' (genealogical abbreviation).
'initially' says to put letters next to each other.
'racist' anagrammed gives 'rastic'.
'rastic' after 'd' is 'DRASTIC'.
(Other definitions for drastic that I've seen before include "Extreme - violent" , "Radical, extreme" , "Radical, far-reaching" , "Grave" , "Thoroughgoing" .)