Italian river? Old river not very good (4)
I believe the answer is:
poor
'not very good' is the definition.
Both the answer and definition are adjectives. Maybe you can see a link between them that I can't see?
'italian river? old river' is the wordplay.
'italian river?' becomes 'po' (river in Italy).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'river' becomes 'r' (abbreviation).
'po'+'o'+'r'='POOR'
Can you help me to learn more?
(Other definitions for poor that I've seen before include "Penurious" , "Shoddy" , "In want; below par" , "mean" , "Without means" .)