Studies points following detective’s case (4)
I believe the answer is:
dens
'studies' is the definition.
(I've seen this in another clue)
'points following detective's case' is the wordplay.
'points' becomes 'ns' (N is an example).
'following' means one lot of letters go next to another.
'case' says to hollow out the word (remove centre letters).
'detective' with its middle removed is 'de'.
'ns' after 'de' is 'DENS'.
(Other definitions for dens that I've seen before include "Habitations of wild animals" , "Man's" , "Studies" , "Habitats of some wild animals" , "Lairs" .)