Quarrel unexpectedly at event involving daughter (8)
I believe the answer is:
vendetta
'quarrel' is the definition.
(I have seen 'Violent quarrel' mean 'vendetta' so perhaps 'quarrel' could also mean 'vendetta')
'unexpectedly at event involving daughter' is the wordplay.
'unexpectedly' indicates an anagram.
'involving' means one lot of letters goes inside another.
'daughter' becomes 'd' (genealogical abbreviation).
'at'+'event'='atevent'
'atevent' with letters rearranged gives 'venetta'.
'venetta' placed around 'd' is 'VENDETTA'.
(Other definitions for vendetta that I've seen before include "intense feud" , "Murderous feud" , "A prolonged feud of Sicilian origin" , "Private feud" , "Violent feud" .)