Preliminary preparation (9)
I believe the answer is:
spadework
'preliminary preparation' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for spadework that I've seen before include "Necessary preparation - digging?" , "Routine preparations for an undertaking" , "Preparatory labour (in the garden?)" , "Routine preparation" , "Arduous but necessary preparation" .)