Setting up (12)
'setting up' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for establishment that I've seen before include "Power-wielding class" , "Those in power" , "Action of setting up on a permanent basis" , "Institutionalized authority" , "Power-holding class" .)
'setting up' is the definition.
('establish' can be a synonym of 'set up')
This is all the clue.
(Another definition for establishing that I've seen is " Founding".)