Piece of information I came across after revolution (4)
I believe the answer is:
item
'piece of information' is the definition.
(I've seen this before)
'i came across after revolution' is the wordplay.
'came across' becomes 'met' ('meet' can be a synonym of 'come across').
'after revolution' says the letters should be written in reverse.
'met' backwards is 'tem'.
'i'+'tem'='ITEM'
(Other definitions for item that I've seen before include "Unit; detail" , "Bit of news to broadcast" , "Part of a list" , "Article (on list or in news)" , "Loving couple" .)