Author Tolstoy initially confined (4)
I believe the answer is:
pent
'confined' is the definition.
(similar in meaning)
'author tolstoy initially' is the wordplay.
'author' becomes 'pen' (to pen something is to author it).
'initially' indicates taking the first letters.
The first letter of 'tolstoy' is 't'.
'pen'+'t'='PENT'
(Other definitions for pent that I've seen before include "Closely confined" , "enclosed" .)