Vast amount Italian writer picked up with article (5)
I believe the answer is:
ocean
'vast amount' is the definition.
(I've seen this in another clue)
'italian writer picked up with article' is the wordplay.
'italian writer' becomes 'eco' (I've seen this before. I am not sure about the 'italian' bit.).
'picked up' says the letters should be written backwards.
'with' is a charade indicator (letters next to each other).
'article' becomes 'an' (indefinite article).
'eco' reversed gives 'oce'.
'oce'+'an'='OCEAN'
Can you help me to learn more?
(Other definitions for ocean that I've seen before include "Huge expanse" , "lot of liquid" , "Large stretch of sea" , "One of the Seven Seas" , "eg Arctic" .)