Detested duke seen strangling son (8)
I believe the answer is:
despised
'detested' is the definition.
(I know that detested can be written as despised)
'duke seen strangling son' is the wordplay.
'duke' becomes 'd' (abbreviation).
'seen' becomes 'espied' (I've seen this in another clue).
'strangling' indicates putting letters inside (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 "held in contempt" , "Felt contempt for" , "Scorned" , "Had contempt or scorn for" , "Looked down on" .)