Detested daughter seen strangling son (8)
I believe the answer is:
despised
'detested' is the definition.
(I know that detested can be written as despised)
'daughter seen strangling son' is the wordplay.
'daughter' becomes 'd' (genealogical abbreviation).
'seen' becomes 'espied' (I've seen this in another clue).
'strangling' means one lot of letters goes inside another (I've seen this in other clues).
'son' becomes 's' (genealogical abbreviation for son).
'espied' going around 's' is 'espised'.
'd'+'espised'='DESPISED'
(Other definitions for despised that I've seen before include "Scorned" , "Detested" , "Looked down on" , "held in contempt" , "Felt contempt for" .)