Political party putting approach in writing once (6,1)
I believe the answer is:
linear b
'writing once' is the definition.
(ancient Greek script)
'political party putting approach in' is the wordplay.
'political party' becomes 'lib'.
'putting approach' becomes 'near' (I can't explain this - if you can you should believe this answer much more).
'in' is an insertion indicator.
'lib' enclosing 'near' is 'LINEAR B'.
(Other definitions for linear b that I've seen before include "Early signs" , "Old script" , "Ancient writing used at Knossos" , "Ancient Minoan script" .)