Wicked family producing ill feeling (3,5)
I believe the answer is:
bad blood
'ill feeling' is the definition.
(I've seen this before)
'wicked family' is the wordplay.
'wicked' becomes 'bad' (associated in meaning).
'family' becomes 'blood' (blood can mean one's family).
'bad'+'blood'='BAD BLOOD'
'producing' is the link.
(Other definitions for bad blood that I've seen before include "Hatred - ill-feeling" , "Rancour" , "Hostile feelings" , "Hostility or ill-feeling, from tainted gore" , "Ill-feeling (between people)" .)