Private eye has good hog (3)
I believe the answer is:
pig
'hog' is the definition.
(I know that pig is a type of hog)
'private eye has good' is the wordplay.
'private eye' becomes 'PI' (synonyms).
'has' is a charade indicator (letters next to each other).
'good' becomes 'g' (abbreviation).
'pi'+'g'='PIG'
(Other definitions for pig that I've seen before include "Unforged metal" , "Empress of Blandings?" , "Porcine animal" , "Glutton" , "Eat greedily" .)