Politician concealing an article or plan (3)
I believe the answer is:
map
'plan' is the definition.
(plan can mean a map of something)
'politician concealing an article' is the wordplay.
'politician' becomes 'mp' (Member of Parliament).
'concealing' is an insertion indicator (back).
'an article' becomes 'a' (the indefinite article in English).
'mp' placed around 'a' is 'MAP'.
'or' is the link.
(Other definitions for map that I've seen before include "(Make a) geographical representation" , "Sketch" , "face" , "Geographical plan" , "Diagram of an area" .)