Evil family shows animosity (3,5)
I believe the answer is:
bad blood
'animosity' is the definition.
(synonyms)
'evil family' is the wordplay.
'evil' becomes 'bad' (associated in meaning).
'family' becomes 'blood' (I've seen this in other clues).
'bad'+'blood'='BAD BLOOD'
'shows' acts as a link.
(Other definitions for bad blood that I've seen before include "Ill feeling, animosity of sanguinary sort" , "Hatred - ill-feeling" , "Ill-feeling (between people)" , "Hostility or ill-feeling, from tainted gore" , "Rancour" .)