Policy document that is easy to see? Nothing to it! (9)
I believe the answer is:
manifesto
'policy document' is the definition.
(document of a political organisation's policies)
'easy to see? nothing to it' is the wordplay.
'easy to see?' becomes 'manifest' (manifest means obvious or apparent).
'nothing' becomes 'o' (looks like zero - 0).
'to it' means one lot of letters go next to another.
'manifest'+'o'='MANIFESTO'
'that is' acts as a link.
(Other definitions for manifesto that I've seen before include "See 6" , "Statement of policies" , "Soften aim (anag) - platform" , "set of political proposals" , "party programme" .)