Refuse in private room close to study (4)
I believe the answer is:
deny
'refuse' is the definition.
(I know that refuse can be written as deny)
'private room close to study' is the wordplay.
'private room' becomes 'den' (a secret room or location).
'close to' says to take the final letters (the close/ending of).
The last letter of 'study' is 'y'.
'den'+'y'='DENY'
'in' acts as a link.
(Other definitions for deny that I've seen before include "Contradict, refuse" , "Refuse to give" , "Declare untrue" , "Controvert" , "Reject as true" .)