'Brilliant' star daughter somehow spoilt (7)
I believe the answer is:
defaced
'somehow spoilt' is the definition.
'defaced' can be an answer for 'spoilt' (defacing is a kind of spoiling). I'm unsure of the 'somehow' bit.
'brilliant star daughter' is the wordplay.
'brilliant' becomes 'def' (I've seen this before).
'star' becomes 'ace' (synonyms).
'daughter' becomes 'd'.
'def'+'ace'+'d'='DEFACED'
Can you help me to learn more?
(Other definitions for defaced that I've seen before include "made to look bad" , "Spoiled or damaged the surface of" , "Blemished" , "Spoiled the appearance of" , "Disfigured" .)