Study some precedent (3)
I believe the answer is:
den
'study' is the definition.
(den can mean an office or study)
'some precedent' is the wordplay.
'some' says the answer is hidden in the clue (some parts of the word are used).
'DEN' is hidden in the letters of 'precedent'.
(Other definitions for den that I've seen before include "Animal shelter" , "Hidden lair of an animal" , "Animals' shelter" , "Hideaway" , "Cave" .)