Study many points (3)
I believe the answer is:
den
'study' is the definition.
(den can mean an office or study)
'many points' is the wordplay.
'many' becomes 'D' (Roman numeral for 500).
'points' becomes 'en' (two compass points).
'd'+'en'='DEN'
(Other definitions for den that I've seen before include "Wild animal's lair" , "Animal's home or gent's study" , "Animal shelter" , "Habitation of wild animals (3)" , "Animals' shelter" .)