Piece of news I came across in review (4)
I believe the answer is:
item
'piece of news' is the definition.
(I've seen this before)
'i came across in review' is the wordplay.
'came across' becomes 'met' (to come across is to meet or encounter).
'in review' says the letters should be written backwards.
'met' back-to-front is 'tem'.
'i'+'tem'='ITEM'
(Other definitions for item that I've seen before include "Unit; detail" , "couple making out {TIME}..." , "Object, detail" , "Two lovers as one" , "two with a link" .)