Stupid to cut short studies (4)
I believe the answer is:
dens
'studies' is the definition.
(I've seen this before)
'stupid to cut short' is the wordplay.
'stupid' becomes 'dense' ('dense' can be similar in meaning to 'stupid').
'to cut short' means to remove the last letter.
'dense' with its last letter taken off is 'DENS'.
(Other definitions for dens that I've seen before include "Lairs" , "Habitats of some wild animals" , "Habitations of wild animals" , "Studies" , "Man's" .)