Establish unit: set it in motion (9)
I believe the answer is:
institute
'establish' is the definition.
('institute' can be a synonym of 'establish')
'unit set it in motion' is the wordplay.
'in motion' indicates anagramming the letters (I've seen this in other clues).
'unit'+'set'+'it'='unitsetit'
'unitsetit' anagrammed gives 'INSTITUTE'.
(Other definitions for institute that I've seen before include "college" , "order as before" , "Establish, educational organisation" , "Educational organisation, found or begin one" , "Found; an establishment" .)